You can create the characters yourself
So, some players are not exactly fond of character creation. I have had players that would love to play a campaign, but I would have to give them a ready character, because they simply don't like the character generation thing, especially the mechanics part. So, what I usually do is:
Ask them what kind of character they want to play. From the comments, it seems they have some idea about that: one wants a paladin, one wants a spellcaster, leaning towards a bard.
Get more details from them about their characters. What kind of paladin? A vengeful one, a naturalistic one? Try to give them a high level idea about their choices, and then build the character accordingly.
For things that are not mechanics (like personality, background...), just ask them to have a well defined portrayal of their characters.
Note that this only works if the campaign is not particularly challenging, as the concept of the character that they want to play may lead to a subpar character. Some subclasses are simply weak, although their concept is nice. They surely can still be fun to play, but if the campaign is challenging, then they most likely will not be fun (it's not fun to feel useless or a burden).
Also, for some other players, it might be important to actually feel like they created their own characters, so, in that case...
Help them as much as you can in narrowing their choices
This will be similar to Austin's answer. I follow a systematic way of choosing a class for new players, which is the following:
First, I narrow it to Spellcasters, Martial fighters or a mix of both. By the way, I consider Warlock a mix of both.
If they choose spellcasters, I explain the distinguishable features of Bards, Wizards, Sorcerers, Clerics and Druids. If they go for martial, I ask them whether they prefer melee or ranged combat, and then proceed to explain the idea behind Rogues, Fighters, Barbarians and Monks. If they choose the mix, I explain Paladin, Ranger and Warlock, as well as Eldritch Knight and Arcane Trickster.
Once they have chosen their class, I usually explain what each attribute does and how it is important to their class. So, if they chose to play a ranged Fighter, I will explain that Dexterity is what is going to be used for their attacks, as well as defining their armor, Con will provide them health and the overall utility of the other attributes.
Then, once they understand the importance of each attribute to their class, they are ready to choose their race. By then, it should be clear that choosing the Half-elf for the Barbarian is not the best idea - but if they want to do that, sure.
"Finally", they can distribute the attributes. This should be easy. I found out that using the Default system is not a huge problem for most campaigns and is quite helpful for new players, although I personally prefer to let them point-buy it.
So, with this, as for mechanics, it is just a matter of choosing equipment, but being fair there isn't much choice here, and, for spellcasters, spell selection. Spell selection is very tricky and usually requires guides for new players. Read my section below on my thoughts on it, but anyway, this would require you providing a somewhat more careful and close help to them, either by a zoom call or something else. If you really can't arrange that, then I would ask if choosing the spells is really important to them - if it is not, go back to the previous section, if it is, refer them to decent guides. Honestly, if they don't have time to read a guide, playing a spellcaster will be harsh.
For subclass choice, it should be simple by now, as it is already narrowed to a class (and depending on their choices, even to a subclass already). Again, you can explain the subclasses available, their major distinguishable characteristics and let them choose.
Then, finally, for their stories, personality and everything else that constitutes the role-playing itself, I never found it to be a problem even for new players. They usually struggle in the mechanics, not in the "character creation" from a storytelling point-of-view.
Now, something that I consider that should be said here...
You might be overshooting
So, from what I understood, there are many limitations for the campaign. For whatever reason, the resources for your party are quite limited (they don't have access to roll20, you can't choose the platform, they don't have access to the books) and the players are busy people that, from what it seems, can't spend too much time reading, studying and understanding the system by themselves. Even for simple communication between you, it may take a few days.
Then, with all of these limitations, you are starting a 7th level campaign. I will be straight forward here: this looks like a bad idea. The new players will be overwhelmed. Usually, it would take weeks playing regularly for characters to get to 7th level. Players would have accumulated dozens of hours of experience playing the system. From my experience, throwing so many mechanics, spells and features all at once has a very high chance of making them not wanting to play any more, simply because it is not fun to play when you don't understand what is happening. In particular, I strongly recommend against high level full casters for new players. There are way too many spell choices and, even if the spells are given, too many spells to remember effects and understand in what situation which one should be used, unless they can actually spend some free time reading the spells and some guides.
Either way, I understand that these are limitations imposed on you by the library, but I would certainly at least a few sessions with the new players at low levels (at most 3) before throwing them at the 7th level campaign. You said they "knew it was going to be this way when they signed up" - but did they really? They don't know how to make a character sheet (as per this question), so how can they understand how complex it is to start a campaign at 7th level? So, please, consider running a low level adventure with the new players so they can get used to the basics of the system (attack rolls, saving throws, AC, HP, ability checks, (dis)advantage, etc) before they have to play with a character designed for someone with more than 30 hours playing the system already.