AP connectivity through Site to Site VPN's

I have 3 sites that have TZ300's. One is a Main site with DHCP Range 192.168.0.x/24, the other two sites are connected through p2p VPN's each having a different DHCP Range. One has a range of 192.168.1.x/24 and the other has a range of 192.168.2.x/24. The all three sites have Ubiquiti AP's for wireless. The Main site has a Ubiquiti Cloud Key Gen2. I need to know what I need to do in the three firwalls so that the Ubiquiti Cloud Key in the Main site can communicate with the Ubiquiti AP's in the remote sites.