Online Seasons couch co-op ps5

I want to play online seasons with my friend using my PlayStation and 2 controllers.

However whenever we try and add a controller it says we cannot process your request.

ive been looking into it and it looks like the other person may also need to have an active ps subscription to play with me even if they log in as a guest on my ps5. Surely this isn’t the case? In the past on Xbox we’ve been able to add a guest and play online seasons no problem