After you have sent our system an invitation, you will receive a confirmation email with your code. However, this is only to notify you it is complete and you will not need this email.
 
After sending the invitation and waiting a few moments (this can be anywhere from a few minutes to an hour), navigate back to your User Permissions page and you will see the invited email address (i.e., "EXAMPLE@sc.sellerlabs.com") as a Pending User. Click on "Confirm" next to the code and you will get a message that reads "You have successfully confirmed Seller Labs as a Seller Central User".
 
From this screen, click on "Add User Permissions".

All of the permissions should be set to "None" by default. Select "View" permissions for Manage Orders found under the Orders section.

Next, find the Reports section. Select "View & Edit" permissions for Business Reports, Sales Summary and "View" permissions for Feedback.

After selecting those two options, click the "Continue" button at the bottom of the page.

Once those steps are completed, the system will start to request the additional details needed for your account to begin working as expected. This can take a 24-48 hours to fully complete.