Hello Ximieghien66
Welcome to the SBB Community?
I could not find the correct place to buy them in the SBB App
Why is that? SBB can indeed sell all public transit tickets.
This gave me 3 PDFs that I have to physically carry to travel on.
In our country, a PDF is an electronic document, we do not carry it physically; thus, it is perfectly fine if you show it to the conductor from your phone or computer. On the other hand, you must present your physical passport or identity document together with your ticket.
It is not possible to add tickets to the SBB app from third-party resellers; they only appear in the app if they were purchased through SBB using the own user account.
Kind regards,
Roland