Thank you Bryle.
I already had an existing add-on on my multi-site.
So I already did those instructions starting with Step 4.
After I click on the link “If you bought new add-ons, then follow this link to refresh your connection.” nothing changes.
The “All Addons” box is not enabled.
I keep getting the message “Your paid access to UpdraftPlus updates for this site has expired. You will no longer receive updates to UpdraftPlus. To regain access to updates (including future features and compatibility with future WordPress releases) and support, please renew.”
I suspect there is an issue with my account provisioning.
As I said, when I go to the Licences page, it says:
“You have 9 available licences
Update subscription expires: 2019-03-29. (9 times)”