Can I fold a rooftop tent when it is wet?

The same applies as for a normal tent.
You can fold the rooftop tent wet/damp. If it is very wet, you can wipe it down with a towel beforehand.

It is important to close all windows and doors completely when the tent is wet, so that water cannot come through the windows onto your mattress. If you have folded up a wet tent, you should do so within 48 hours to prevent the tent from going mouldy.

When not using your hybrid, hardshell or softshell roof tent for a longer period of time, always make sure it is clean and dry.

If you are storing a softshell roof tent for a longer period of time, it is advisable not to fit the cover, which allows the fabric to air properly. Make sure that mice and other vermin cannot get into your tent.