Add New Contacts from Send Update Request

We have some Smartsheet users on our Enterprise plan who are able to add contacts when sending an update request.  I am the owner of the sheet and I do not have the selection button to add a new contact as shown in screenshot labeled Capture 1.  However, 3 users who are not licensed and only have Editor permissions have the selection "ADD NEW" button highlighted in yellow in screenshot labeled Capture 2.

The third screenshot was found on the Smartsheet learning and help articles, but does not provide guidance if that button is missing.

FYI, I have tried in both Google Chrome and IE.

Thanks in advance for any feedback or solutions.

DeLeah Vogt