Git sync normally "just works", but because there can be complex changes that cannot be resolved automatically, sometimes you will run into an error that has to be fixed by hand.
(This is a good thing; Git is keeping your files safe, and tries very very hard to make sure they don't get messed up.)
For now, find a Massive Wiki or Git "concierge" in your community and ask for help.
You can avoid most problems by making sure you are not editing the same lines in the same file as other people might edit around the same time.
So, coordinate over a chat or other communication tool, and if you edit different files, or even different sections in the same file, you will generally be okay.
If you need to edit the same lines, consider getting on a video call and using HackMD. See the instructions elsewhere about "Connecting HackMD to a Wiki Page".