After searching a lot on the Internet about the problem that I'm having when I try to register the gitlab runner, I was able to verify that the problem was related to SSL certificates. I've looked for solutions to the problem and came across these two "solutions":
Before I tried to apply these "solutions", the error that appeared after the runner's registration attempt was this:
Previous ERROR:
And after I tried to apply the two procedures above, the error that now appears is this:
Current ERROR:
I have no idea what these IP SANs are or how to solve this problem. Thanks in advance to anyone who can take a little time to help me with this problem.