Portal URL for Use in a Link?

Portal URL for Use in a Link?

Maybe I'm missing something, but I'm trying to find a link that I can use on a webpage to take clients to their portal. I get that they'll need to log in--that's fine. But is there an open URL that I can use, or it would be different for each client?

Thanks!

EDIT: I did find on the Settings > Branding > Portal Settings page a portal link:  https://books.zoho.com/portal/COMPANYNAME

Is that universal? Thank you :-)