option for “sign in with apple” does not appear

Have you followed the instructions here under "Sign in with apple on other platforms" https://support.apple.com/en-us/HT210318

I think it's mostly a safari implementation, but it should work in firefox too if you're signed into icloud.

thanks for your quick response, eve. i asked because the option to sign in with apple *doesn’t appear*, only google, fb, and amazon.