HELP please. How to get to WP Dashboard

Hello, I am a relatively beginner designer, and I can’t log into my client’s WP Dashboard through the https://YOURDOMAIN.com/wp-admin method.
She has an .ORG site, and also has username & password to WP.org, which I used and works. However that is not tied to her website.
I know once in WP Dashboard, I can go to settings and set up my own username and password to get in afterword. However, I can’t even get in to the Dashboard. She does not seem to know her admin username and password to go through the /wp-admin way.
Do you know of a way to get in? I can’t seem to be able to find a # to contact WP direct.
Thank you!!