Hello Kenji
Welcome to the SBB Community.
We are a travel support forum run by volunteers, we are not the SBB Customer Service. If you need instant help, please call SBB: +41 51 225 78 56 (24/7). On this platform, however, we reply when time permits, although we are fast in responding.
Please keep in mind that you have not purchased a SwissPass, you have purchased a Swiss Travel Pass.
SwissPass= for Swiss residents
Swiss Travel Pass= for tourists.
Therefore, you cannot make use of the SwissPass and can purchase the ticket on-site only. The Matterhorn Paradise website is very confusing and causing us a lot of questions. We wish they would finally precise their website. As it is a private provider, SBB has nothing to do with this offer.
But there is no issue: we anyway do not recommend purchasing mountain excursion tickets in advance. What if the weather is bad or stormy and you do not want / cannot do this excursion? It will mean you have to request a refund. When purchasing tickets once you are in Zermatt, you also safely know the weather forecast for the next days.
Keep in mind, Swiss people love niceties like the Japanese do. Saying hello before asking a question is considered polite in our culture.
Kind regards,
Roland