Did you fill out the full URL, i.e., https://botsin.space?
On my test install, I’m able to get a client ID/secret from that server just fine:
I didn’t, I just typed botsin.space as that had worked in other plugins I was testing.
My apologies, I will update my review! It may be worth adding a note to say to include the ‘https://’ or to add a filter that adds it if the user has missed it?
OK, I’ll clarify! (And maybe accept “regular” text input, too, in a future version.)