Information for everyone shared by our engineering team:
"We tested it and just ran into the same issue in one tenant, but not in another, and I think I can explain why.
The logging extension creates a Client Application in the tenant when it is installed. Our basic tier plan places a limit of 10 Clients in a tenant, and I got this same error when trying to install an extension that was at that limit.
So, if you want to install this extension, you’ll have to delete one of your clients first. In the mean time, I will place an issue in our backlog to improve the error message so its root cause is more obvious."