Trying to get the Nashvilla relic and into the Hunting Grounds. Figured this was the right tool for the job. But. . .I can't equip it like the servo suit, I can't wear it like a back pack, I can slot in on my belt but when I click on it and try to use it to jump my curser turns into a nope circle. . .

Suggestions?

First make sure your Devices skill is enough for yousing JatPack. Should be about 60. If you have needed devices skill level the ability to use JetPack is unlocked.
And second if you have a recuired skill level you maybe clicking to far from the limit of the jump. Check jump distance in an item description
And yes, JatPack is used from the belt slot

Not intending to reactivate a dead discussion , but if others seek for same answer then at the moment (I use Epic Games Store version as of 2022) then in my game skill is 'Contraptions' and needed skill is level 3 which , and I am not sure , appear to be 90 skill points needed assigned to get ! (a hell of a lot if anyone asks me !)(considering how much more there are to use points on !)

True but any build in this game should be made to get maximum skill points for that exact reason, you need a lot of skill points to cover stuff, so sadly the way the game is designed you will want max 10 brains for max skill points per level, and 1 of 2 factions (+1 brains or +2 skill points) plus picking up perks that boost skill points. You can never have enough.

Doing that you'll get enough skill points to use jetpacks at some point. Really so far i have just found them useful for extra loot in places you normally have to jump to, which i guess is the reason they are in the game so you can get extra loot, or not worry about extra loot.

But with my character i found it pretty easy to get skills up enough to get the jetpack and various things. I worked on influence and criminal early for maximum looting and conversation experience since there is A LOT more of that then fighting experience. Then i started boosting my weapon, science, tech, medicine etc. I found only 1 weapon was needed early on and was more important to boost those 2ndary skills.

Later when you can get companions they will help in the fights, but there is a lot of experience and loot to gain early game with stealing, looting, talking your way out of being caught stealing, fights and such.