SAML Creation - Find IDP without metadata?

Hi there -

I just setup a SAML app with a dev account and everything seems to be working smoothly. The call back url works and I am able to login as well. But for production, we ofcourse need the metadata url so that we could identify the IDP and authenticate/assertion.

But there are also other apps like zoom, which just asks for a subdomain, and somehow authenticates the context, without asking for any metadata or ACS url. Any idea how that works?

I want to keep it simple for the end user and the zoom way seems to be the best, but I am not sure how it would work without the metadata url etc.

Note : If this works for IDP initiated login, that should be okay. (SP initiated is not necessary as of now)

Any help would be greatly appreciate here.