These landing pages can be configured within the app, or you can point to an external captive portal of your choice. You should have a 30 day return policy available if you wanted to give it a test run.
Let us know what you think about this solution and if it covers your needs adequately.
That is a great document I couldn't find using a normal search and it almost looks like it will work. Both of the providers linked below require Radius authentication that I do not see mentioned on the link you provided. Can Meraki Go work with either of these providers? Even on the Meraki Enterprise side a request has to be put in to support Radius Accounting so I'm hoping it could be done.