Hello Suchitra
Firstly, welcome to the SBB Community.
It is not possible to add tickets and travel cards to the SBB Mobile app that were purchased through third-party providers or were purchased with SBB yet as guest.
We do not recommend the purchase of tickets with resellers as you could buy all public transit tickets easily through the official channels such as sbb-tickets.cc or, for tickets and day passes, using the SBB Mobile app.
Tourists do not have a customer number; simply click the ‘No customer number’ button if you still want to create an account for future ticket purchases through SBB.
https://sbb-tickets.cc/de/angebote/swisspass-karte/register/2?lang=en
You can still use your already purchased tickets. They need your phyiscal passport or government identity card during ticket check in order to be valid. No passport photos, no photo copies.
Kind regards,
Roland