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