To invite MobileAction to your App Store Developer Account, you should go to the Users and Access page of App Store Connect. Then it will let you invite users as the role of what you choose by clicking on the ‘Plus’ button. Here the administration must invite MobileAction ID which is shown in the last step of the integration page with the role of ‘Admin’ or ‘Marketing & Finance (both)’.
Note: You can look up for the user roles and abilities from that Apple’s page