I don’t have a mac, though this may be of interest / help, mate:-
https://www.youtube.com/watch?v=Q-KbFcmsirw
^ A 5 minute video, with 11 upvotes, and seemingly quite easy to follow.
This seems quite decent too:-
https://www.leawo.org/tutorial/how-to-burn-mkv-videos-to-blu-ray-with-multiple-subtitles.html
Good luck with it - videohelp.com is a great resource with forum for more indepth info etc, and may be worth a look at.