Building a custom FreeBSD kernel

I am trying to build an ARM64 version of the FreeBSD kernel that has Realtek wireless drivers enabled.  I absolutely have to customize the kernel options, as some of the drivers do not allow boot time enabling. 0. I am on WSL 2 using Ubuntu to attempt to make/build the files. 1. First I cloned the repository.

https://github.com/freebsd/freebsd-src.git 

2. Next I cd’ed into the directory called freebsd-src…. 3. Then I attempted to make just the base version doing this:

make buildkernel=GENERIC

Then I get this error:

Makefile:122: *** missing separator.  Stop.

I have read other posts that mention it being an indention issue / expecting tabs but getting spaces, but the directory does not (in my view) have the correct files to change the ruleset.  It also does not have any configure / autoconf files.  What could fix my issue?