The functionality provided by the fbtft module has moved to an overlay in 5.10, you can try to use the overlay to configure your display.
The 4.7.1 is using the 5.4.72 Linux kernel version, if you need an earlier version you may try the 4.6 version, though I'm not sure which Linux kernel version is used in 4.6. Older versions are unsupported, but from 4.6/4.7 you can upgrade to the current RetroPie version and skip any Linux kernel updates.

My advice would be to try and use the overlay method to configure your screen. RetroPie uses a RaspiOS Lite (buster) as a base, so any instructions that apply to RaspiOS (Raspbian) Lite should work on RetroPie also.