Where are you logging in? If it's my.hubitat.com, the hub registration page, or anything else that ultimately points there, your credentials should work.
However, it sounds like you might be talking about hub login security (screenshots are 2.3.9 and older but same idea on 2.4.0):
That is what would you would see if they had this enabled and you navigate to the hub's IP address in a web browser (or find it using findmyhub.hubitat.com or similar). There isn't an easy way to disable this in a way that lets you keep existing settings without their assistance. If they're comfortable giving you this password (it's local to the hub, not connected to their account at all) or the username and the reset from the "Forgot password" link you should see there should work, then you can disable hub login security in Settings or add your own if you want.
But that's assuming this is what you really see.
