45 Drives Storinator - r750 Drivers - Kernel issues

I’ve seen a couple threads on here with users having the same issues I am running into but never a resolution.
I have a 45 drive storinator with pair HighPoint Rocket 750 cards. I started with Rockstor 3.9.1, which as a boot kernel of 4.10, and could never get the drivers to work. HighPoint says their Linux Opensource Driver supports up to 4.9 so I downgraded to Rockstor 3.9.0, which has a boot kernel of 4.8.7. Still having the exact same problem.

“Verifying archive integrity… All good.
Uncompressing R750 Linux Open Source package installer…
Starting install R750 Linux Open Source package …
Checking and building device driver for R750…
Default boot kernel 4.8.7-1.el7.elrepo.x86_64 does not contain essential build tree to build driver.
ls: cannot access : No such file or directory
ls: cannot access : No such file or directory”

Any help would be much! appreciated.