Thanks for the reply! After a reboot, the make process worked, so I followed the rest of the instructions above. Twice, actually.
Now it's just a matter of the adapter not being recognized. It's a TP-Link Archer T4U Plus, which my searches indicated should be an rtl8812au, but so far no lights.
I've managed to get other unsupported adapters working on Linuxes with dkms support, but this is my first attempt with Solus.
UPDATE: My plus model actually uses the 8822bu driver, which I found and installed. Working now. Thanks for responding.