Absolutely. First, you’ll need to know the user's email address and first and last name from the ERP. Then, log in to your xTupleCommerce website and go to People > Add User in the admin bar. From there, enter their email address, create a password for them—they can and are encouraged to change that. Optionally, you can specify that they receive an email notifying them of their user account.
On the add user screen, it is very important to make sure that the "Create xTuple Association" checkbox is selected. This ensures that the information flows between this user and the user in the xTuple ERP database.
Next, start typing their name in the choose an existing contact field. Once you start to type their first name, contact options should begin to appear after a short delay. Select the user from the list of options.
The rest of the fields should auto-populate based on the contact information stored in the ERP. To save, click CREATE NEW CONTACT at the bottom.