Thank you for contacting us and I'm sorry about the issue you're experiencing. mSecure 5 is a brand new app, and mSecure 5 is the first and only version of mSecure to use an account system. Please create an mSecure account to get started in mSecure 5. Please note that you'll want to start by using mSecure 5 on a device that has the previous version first.
You can always download the previous versions instead: https://support.msecure.com/support/solutions/articles/36000064249