I tried a variety of .conf files created from both mullvad’s config generator and also from the cloudflare/Warp wireguard configuration script. It seems that no matter what is in the text box, the ‘Add’ button in your app does nothing. There is no feedback - even visually to demonstrate that it’s being pressed - it could just be an inanimate image as far as I can tell.
To copy paste the files to the box I opened them on computer in text editor and sent the contents by encrypted messenger to the phone. I am not willing to share my own conf files but you can generate your own for free in minutes:
I don’t see how the text gets copy-pasted is much of an issue since there is not any formatting added by the apps I use (text editor or messenger) and the same issue with the ‘Add’ button is present when using the QR code.
I tried the same wireguard configs on the traditional web UI – mullvad’s works straightaway but the cloudflare config needed to be formatted for your copy-pasting tool to work.
I don’t know what you’re seeing on your end, but on my end, the ‘Add’ button just looks unpressable.