Click on Add people at the bottom of the project
Then enter an email (one or multiple) so that your collaborators receive a link with an invitation to the project.
Also, you can send the invitation link, by clicking on which collaborators will get access to the project.
After the collaborators followed by email invitation or link, they will see an invitation window with the avatar and the name of your project.
Collaborators can enter the project after signing up, or log in if they already have a Pibox account.