Most ISPs use a personal login and password, different to each customer. The ISPs own router may be configured using TR069 management. Plusnet certainly does this.
Some ISPs will make such authentication information available in their control pages, others don't expect you to swap the provided equipment and make you call customer services.
BT is probably the odd one out in using a generic logon for everyone.
There is nothing on Zzooms site about using your own router, apart from a little but that is out of date saying that it is possible. I had to muck around to get mine working, well guess work really , using Dynamic IP
Adrian
Desktop machines Mac mini pro with macOS Ventura, also pc Ryzen powered with windows something or other.
Zooming with Zzoomm FTTP,