How do you add a user to the free version?

How do you add a user to the free version?

I just typed a question and accidentally sent it into cyberspace so I apologize if it shows up and this is a duplicate. I am 70 years old and am new to all of this so please excuse my ignorance. I am writing procedures that I want someone to have access to. I don't want to send them as attachments or end up with multiple versions of a procedure. When I signed up for the free version of Zoho it said up to 3 users.

I thought I would be able to have at least another address that I could use for my partner but I can't figure out how to add a user. I guess I could just create another account for her but I wanted to see if Zoho could be used for document control and management in which case I would up-grade.

Any suggestions would be really appreciated. Thanking you in advance.

Warm Regards, Carol