I am having the same issue. I also tried through the App and it does let you select a time zone there but then it just spins for a while and then say "INVALID RESPONSE" and kicks you back to the setup screen.
It seems to be a pretty heavy flaw that the only way to submit a request for support is behind the the broken account setup screen.
Having exactly the same problem when trying to create an account through the webpage.
While trying to make an account using the Meraki Go APP, we get the error:
ERROR - Invalid Response
I'm trying to add my subscription for my GX20 and keep getting "Invalid Response" or "Load Failed" and tips on how to get this in so I can keep my network secure.
You should definitely open a support case for problems or errors generated by the app. This helps give us more specifics about the issue you in particular are facing, and also gives you the opportunity to stay in the loop about the resolution of the issue over time.
Typically the invalid response error is generated when there are poor network conditions. It is definitely worth trying a different network connection to rule that out.