Need to use different log in than Facebook

I need to provide my log in information to a company I do contract work for so that they can log into scheduled meetings if I am unable to attend. Currently I log into zoom using my Facebook account and need to change that to my email plus a password. When I attempt to do as the link below says, I get a message that I already have an account and it won't let me change anything.

https://support.zoom.us/hc/en-us/articles/201362343-Signing-in-without-Google-Apple-or-Facebook