No, you cannot control it like any other mount
If we presuppose that you can use it as a mount at all, the list of restrictions on the hound is extensive and precludes a lot of what mounts are useful for:
It can move through other creatures and objects as if they were difficult terrain. The hound takes 5 force damage if it ends its turn inside an object.
At the start of its turn, the hound automatically knows its target’s location. If the target was hidden, it is no longer hidden from the hound.
The hound appears in an unoccupied space of your choice within 30 feet of the target. Roll initiative for the hound. On its turn, it can move only toward its target by the most direct route, and it can use its action only to attack its target. The hound can make opportunity attacks, but only against its target. Additionally, while the hound is within 5 feet of the target, the target has disadvantage on saving throws against any spell you cast. The hound disappears if it is reduced to 0 hit points, if its target is reduced to 0 hit points, or after 5 minutes.
- it can only move toward its target by the most direct route
- it can only use its action to attack its target, and can only make opportunity attacks against its target
- it only lasts for a maximum of 5 minutes
So to answer your question, no, it does not move as you direct it, it moves in a straight line, through objects and creatures if needs be, towards it's target and can only use its action to attack its target.
A slightly more liberal DM may also allow it to Dash towards it's target if it is too far away to attack it...but that's up to the DM.
You may not be able to use it as a controlled mount anyway
Controlled mounts have this requirement:
You can control a mount only if it has been trained to accept a rider.
Your Hound hasn't been trained to accept a rider, therefore you can't control it.
Its likely your Hound is intangible, and likely unwilling to be a mount even if it is tangible, and thus can't be effectively mounted in the first place
In order for a creature to be a mount in the first place it must be
A willing creature that is at least one size larger than you and that has an appropriate anatomy can serve as a mount, using the following rules.
When you summon the Hound you
call forth a howling creature of darkness to harass your foes
move through other creatures and objects as if they were difficult terrain
Which strongly suggests it is intangible and thus cannot be mounted. So while it is one size larger than you, (you being Small, it being Medium), an intangible creature does not have the relevant anatomy for mounting.
In addition the description of the Hound doesn't lend itself well to being interpreted as it being a "willing creature" to be mounted even if it is tangible.