Ensure that your phone has internet access.
Open the Table page
Press the 3 dots on top right corner to open menu
Select Add People
Press Add new collaborator button in the next screen
Enter email ID of the other REGISTERED
Press Done button.
In a few seconds, user will be added.
This collaborator can add new rows via form.
You can restrict him to see rows added by him and not view rows added by other collaborators.
Can view all rows i.e. rows created by him as well as created by other collaborators.
You can restrict him to see and / or edit your choice of columns. Just tick mark the columns while adding him as collaborator.