Once your administrators have been added (either manually one at a time or in with a spreadsheet upload), be sure to invite them to the system so they can accept their role.
1. Go to your Administrators tab.
2. Select the users you wish to invite (using the check box next to their name), and click on the "Send Invites" link in the Quick Tasks(under the 'Message Administrators' button) and follow the prompts.
3. They will receive and email to their inbox:
When they click on accept invite they will be directed to the below page to sign up, or log in:
4. Once they are logged in, if they are a group admin and you have not added them to any groups just yet, they will see this message: