Are you trying to set up Nostr Wallet Connect (NWC)? Because WoS does not support that as far as I know.

I have all NWC fields empty and Amethyst redirects me to any LN app on my phone (I think Android manages that). I did not set up anything.

Previously I had NWC with cashu.me but that just stopped working for me at one point. Don't know why..