Active player here, I got rank 4 on ground and air (US), Im looking for a squadron just to grind vehicles as quickly as possible (max activity). If comms are necessary, I got discord and I speak both English and Spanish, as well as basic German. My schedule changes because of rotatory shifts at work, but on the weekends I usually have some time to spare.
Your best bet is to go ingame and find squadrons with slots, and open acceptance, and just be sure to find one with about 200k activity.
Anything lower you may find you won’t get the 20k RP each cycle.