Hi Henrik,
It seems to work correctly for me on demo.mojoportal.com. I enter a name and address, phone and email in the customer information, click the update/confirm button and then the pay later button is enabled and I click it and it works.
The only reason the demo site shows the test mode warning (it is not an error just a warning) is because it is configured also for Authorize.NET using a test account, so we don't want users entering real credit card numbers.
Best,
Joe