Chillax_33 - your first post - Welcome to the forum. So that we are talking about the same thing, your Atlas Straps are Daisy Chain (sewn loops), right? And your issue is the wrap around the tree sliding?
Note that a whoopie sling is used as a connection between the hammock and the wrap around the tree. The woopie sling does not wrap around the tree. So you could have the same issue with that. Yes, you could wrap with the whoopie sling, but the cord could cut into the bark, and usually most "formal", i.e., park campsites, require a minimum of 1 inch webbing around the tree. It's the right thing to do.
Without an image of your setup, there's a bit of a guess. Are you orienting the tree wrap so it comes off the side of the tree or the middle? Also, Atlas straps - at least when I got mine - had a "tree end" - about a 2-foot tail with no loops - and a "loop end". If the tree diameter is too small, you could wrap the tree end around twice or just wrap the tree with the loop end instead.
If you could upload a photo of the tree and the strap where it is slipping, so we can see what you are doing, that would be a great help.
A short answer would be to wrap around the tree multiple times, but there might be something else going on.