I use keepassXC on linux.
Copy the secret key from the url.
otpauth://totp/Lemmy.world:username?secret=xxxxxxxxxxxxxxxxxxxxxxxxx&algorithm=SHA256&issuer=Lemmy.world
Paste that here:
I tried all this, I did get keepass to provide the 2FA code, but lemmy won't accept it. I had to reset my password so I can get back in.