>>537968635
Ave murica is something like half a year away.
Collab banners have the 6* guarantee at the 120 rolls mark.
You could always do old events to get the free units from there if you don't want to roll. Have you used recruitment often? If you are that new there should be plenty to get from there.
You've unlocked IS right? There are these "Monthly squads" and "Deep investigations", which should give you some materials to get going.