Hello,
There are a few macbook users here. Forum search is working.
On the archived forum are probably more topics about. One good resource is here
https://wiki.archlinux.org/index.php/MacBookPro11,x
even tho is not exactly for the 2015 model.
Another lengthy but useful discussion is here
https://bbs.archlinux.org/viewtopic.php?id=198051
If you have specific questions or issues, is better to address them separately in a help request.