I can't connect to headset from my meta app

I need to pair a new controller to my headset since there is one broken. For this I need to go to the META app on my phone and go to the "Headset settings" but I am unable to because it won't connect to my headset???  Strange is that I can Cast from the headset to my mobile, so there is a connection? Is there another way to pair my new controller? Also tried using the PC but no option for pairing a controller (button is not working there)