In order to add a new user in Xero, you will need a user role equipped with the 'Manage Users' permission.
Click on your company name (top left).
Select 'Settings'.
Select the 'Users' menu.
Click the 'Invite a user' button in the top right corner.
Enter the user's first and last name, plus their email address.
Select the options to give access to 'Projects' and 'Business and accounting'
For Project, select 'Admin' access.
For Business and accounting, select 'Advisor', check yes to 'Bank Account Admin' and check yes to 'Manage Users'.
Send invite.
The invited user has 14 days to accept the invite before the link will expire.
To resend an invite:
Click on your company name (top left).
Select 'Settings'.
Select the 'Users' menu.
Click the name of the intended user.
Click 'Resend Invite'.
Click 'Send Invite'.