Export WAV with loop markers?

I have been searching the web for an hour now trying to figure out how the hell you are supposed to insert loop markers and export a wav file with them.

I know this can be done because I’ve done it before, years ago, in an older version.
Now that pretty much every search engine sucks and never shows you what you are actually looking for, good luck finding any useful tutorials. Most of them stall and waste your time only to then literally “make a looping file” by hand. That’s not what I want. My music is ready to go. I just need to export a wav with markers so that the game engine knows when to loop it.