You’ll need to install the OSMC kernel headers (rbp2-headers-4.19.122-2-osmc) and run the ln command shown in this post: Driver support for Archer T2U Plus (wireless usb adapter)? - #11 by dillthedog.
Unfortunately, DKMS isn’t currently supported in OSMC, so you’ll need to make the module manually. If the build fails, it might be because of an ongoing problem with the headers package. See Has anybody tried to install Wireguard? - #28 by dillthedog for a workaround.