Hello ngluaneng
Welcome to the SBB Community.
We are a customer support page run by volunteers, not the Customer Support.
That said, the answer to your question is: not possible.You can only link passes if they were purchased as a registered user, not as guest. And even then, a customer number is not assigned to tourists. It is sufficient to authenticate with the SBB Mobile App using the same username / password as created for sbb.ch before purchasing the travel passes. The latter will automatically appear on the SBB Mobile app as well.
What can you do now, since you cannot add the Swiss Travel Pass to your SBB Mobile app retrospectively?
Simply use the PDF with the QR code that you have got, together with your physical passport (no photos on smart phones, no photo copies of it).
The customer number is assigned to residents abd this only for travel cards, yet not to tourists for travel passes.
And, please:
Never publish ticket details on a publicly accessible page; your ticket data as well as your personal data can be abused. We therefore deleted the sensitive data.
Kind regards,
Roland