I am finding that the lack of integration among the various parts of Zoho is really confusing.

I started with a Zoho account.  Then I started using it for Zoho Business.  It's not clear if they are all part of the same space or not.

Then I registered a custom domain.  So I had mail addresses where some had a 'zoho.com' domain, and others had that domain.   It seemed pretty arbitrary which one was active or relevant during a particular session.

I add users to Zoho Projects, but it's unclear if they are new independent Zoho accounts, or subordinate to the account that I created them under.  They seem kind of independent, but they don't have admin privileges so in that sense they are subordinate.   Same with Zoho Business, when I added users under the Users category in the control panel.

Do  you have all this documented somewhere?   Should I even be worrying about this, or is  your basic philosophy for users to do whatever just works at that moment?