I just uploaded my first audio here: https://web.roblox.com/library/6686403524/Lab-Attack
For some reason, it takes a bit to loop back to the start of the audio. I don’t know if this is by default or if this can be changed. The original file did not have this issue
This is what happens
Try to find the audio then check the setting of it there should be an loop button for it
Like this?
Theres some silence a few seconds before the end. prob an issue with uploading to roblox.
I played the sound inside my studio to make sure 
If you uploaded the audio as .mp3, from what I’ve noticed there will always be a delay at the end of the track, making looping a horrendous experience.
The only fix I’ve found to this delay problem was to reupload the music as .ogg which forgoes the delay entirely, making it sound exactly as outside of studio. I believe there was an engineer response and reasoning for this a while back but I dontt remember the source.