Need help for a game I'm making

Help
1

I need help with something: How do I make barriers so one team can stay in it while the other can’t?

Also, once said team leaves barrier, how do I lock them out?

2

Set the scope to team.

3

welcome @Jellar87 !
You can use triggers and “affecting team” to do that.
So make a barrier in the middle of the map.
Then if a player from the team triggers a trigger that unlocks the barrier and enters the other team’s side, there will be another trigger on the other side that locks the barrier so the person will be locked out. And the triggers and barriers should be modified so that it only affects “team”.