How to solve the connection light keeps blinking, but no successful connection

When the transmitter starts the connection function, it cannot connect to the receiver, try to use the phone
SIM card pin inserted into RESET hole and pressed for 3 seconds to start the reset function, then try to connect.

Can I use it on my camera via an adapter cable?

Cannot

Can the WM820 B2 and C2 microphones record a separate channel?

Cannot,This feature is supported on WM821, and you can purchase WM821

Can I use the adapter to transfer C2 to Apple phone?

Cannot