Hi, and welcome . . . .
Reaper is a bit daunting at first, but your decision to go with it is a good one.
Try this link for setting up:
https://www.reddit.com/r/WeAreTheMus...d_an_akai_mpk/
That ought to get the Akai recognised in Reaper.
Reaper takes some learning to start with. I DO recommend Kenny Gioia's videos here:
https://www.groove3.com/reaper-train...er-4-explained
[These vids are All for Reaper4, but the core details are good for reaper5, certainly fine for learning how Reaper works] I'm sure dedicated Reaper5 vids WILL appear as time goes along . . . .
I have ALL of Kenny's vids - and they are great value, both in the clear way they are presented and the amount of detail.
The "Reaper 4 explained" is more that 7.5 Hrs long and is a great overview.
There is a $15 /month access scheme, but I opted to buy for $40
EACH of the vids has a "sample chapter" that can be viewed for free to give you an idea . . .
Don't forget the Manual itself. Its a big read, but contains lots of detail.
Also available (free to view) are these vids:
http://forum.cockos.com/showthread.php?t=76872
And these, from Paul C :
http://forum.cockos.com/showthread.php?t=154715
Hope that is of some help
Best Regards
parametric