A project user is a person outside of your business who needs to access to a project in the Field View web application or Field View device app.
You send an invitation to a project user to give them access to a project. If the person works on multiple projects, you need to send a separate invite for each project. When you create the invitation, you select the role for the user, which controls what they can see and do within Field View.
The project user creates their own user name and password. However, if the user doesn't do anything, the invitation will expire.