Multiple users

I want to have someone build me a form, but don't want them to have all my login credentials and access to previous forms and my paypal etc. How does collaboration on one form work?

You can add a new sub-user. Click to your avatar, and then click Settings button. After that click User and then Create New Sub User. It will open another view. And you should put the email and you can choose which forms that user it is able to see.