Hello SteveV
To link the Swiss Travel Pass Flex with the SBB Mobile app is not possible. You can use the SBB Mobile app to look up schedules or to purchase tickets for journeys that are not covered by the STP Flex.
What concerns the Swiss Travel Pass Flex, you have to activate each travel day through this website:
https://www.activateyourpass.com/
You can access the QR ticket code for each day through the above-mentioned website, or take a screenshot of the CR code and show it to the conductor, or add the QR code to your wallet.
Please note,
- the Swiss Travel Pass Flex has to be activated before you enter a train / bus / boat.
- you are required to present your physical passport (no copies / no pictures) together with the Swiss Travel Pass Flex to the conductor upon ticket check.
Kind regards,
Roland