Thank you for the thoughtfully outlined tutorial! I'm on the first few steps and trying to "Deploy as web app..." but the screen freezes – see screenshot below. Any idea what's going wrong? I replicated with two google accounts just to be sure.

Not sure @sidbatra - have you had any luck so far? Could be a server issue. Did you properly save the project as a specific name and try to deploy that? Deploying an existing project had no issues for me just now, but would have to walk through all the steps to replicate otherwise.
Thanks @mckennapsean. I gave up for the time being, may be something specific with my gmail accounts.
The error message is not displayed. Use the network inspector and open the underlying sharingService request. The JSON response contains the message:

In your case, it might show a different message.
Ah yeah, you gotta own the script to perform that action, makes sense. Odd they don't have a better error message in their UI.
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Ah yeah, you gotta own the script to perform that action, makes sense. Odd they don't have a better error message in their UI.