Does Zoho Creator/payments allow for authentication?

I am working on a project where the client wants to be able to do a number of things with their database:

Have donors (users) register their information, name address phone etc. via website.
Purchase tickets for events that they have coming up via website. This could be via individual or table.
Register attendance of people attending the events.
Create reports of which donors gave over a certain amount etc.

OK, so I get the basic idea of how zoho creator works and I have created some of the relevant forms. There are a few issues that I am not sure how to work out though:

A captcha type system to make sure their database does not get filled with spam.
How do we avoid having duplicate entries of the same person?
How do we collect payments and have them linked to that existence of that person in the database?

It seems to me that their needs to be some sort of authentication involved. Does zoho allow for some sort of account creation/login to the database so that payments made will be attributed to that user?