Money Can Be Exchanged For Goods and Services
A Jedi has very little in the way of material needs, both because of their lack of attachment and their organization's resources. Sure, some Jedi characters might save up for some items (a top of the line ship, perhaps), but others would have no particular interest in material things outside of their starting equipment. But that doesn't mean they have no use for money: far from it. Because although they don't have a need for or interest in money, they often need to interact with people who do.
Contacts and Information (Knowledge and Defense)
A Jedi has great insight into many matters through their connection to the Force: but they can't know everything or be everywhere. Sometimes, the ability to employ people to search for something or give them information could be useful. And if the desired information can only be found within wretched hives of scum and villainy, then a Jedi's noble demeanor might make them ill-suited to such an investigation.
At times like this, credits could be very useful. You let it be known that you are offering a reward for information about a certain subject or person. Or you could go to a contact you trust and pay them for secrets they trade in. Sometimes, money could be used to acquire literally priceless artifacts: you could put out a reward for information that could lead you to an ancient Jedi Holocron, for example (which you couldn't buy, but might be able to find through a network of well paid informants).
You might even need the money to hire someone with a certain skill set: can the Force hack a computer, or forge a document? If not, then you may need to use those credits to employ an expert. Especially if you hope for this expert to become a long time contact, or a reliable source.
Mind Tricks Don't Work on Me. Only Money
The Force can have a strong influence on the weak minded, but sometimes that's not the best option. There may often be unsavory on downright despicable people you need to deal with whose only interest is money: and having it can make a big difference. From freeing slaves to forgiving a smuggler's debt to bribing a corrupt warlord, money can be a path to righteous deeds when all other options are blocked.
While a Jedi may usually hope to appeal to either their authority, might, or use of the Force to encourage cooperation, these may fall on deaf (or immune) ears. At times like those, the universal message of currency can be very useful.
Wars not make one great
Jedi are martial masters, capable of defeating most foes they can approach. But what if the goal is to build, not to break? What if they encounter a town in need of a school building, or a settlement that needs upgrades to their moisture condensers, or a colony being ravaged by a plague requiring an expensive cure. A jedi may not need much for themselves, but they could acquire money to see to the needs of others. Although most of your adventures will involve foes to defeat, you might encounter some challenges that simply require you to have the resources sufficient to give to those in need.
At the end of the day, money will still have a lot of uses even to characters who don't care about it. Even when you don't need any to buy any things, that doesn't mean you'll never need to buy anything. Whether it's the rewarding the services of contacts, employing expert allies, appeasing the corrupt, or aiding the needy, money can always have a use to a Jedi.
