You can use the pass on trains of the participating companies. So you can travel between the stations served by those trains. Zurich to St. Anton is certainly included.

Do you have any guide to see all the stations that are included on the pass? It seems that all statins are included but I don’t have 100 certainties. 

It is not possible to say that a certain station is included in the pass. It is railway companies that are included in the pass, see list below. Some stations have trains that are run by both included railway companies and railway companies that not are included. 

https://www.eurail.com/en/get-inspired/trains-europe/useful-train-information/participating-railway-companies

The pass is valid to all stations served by the participating railway companies, which is several 10,000s of stations, which is most stations in Europe. There is no map that will show them all. There are good rail maps available, e.g here:

https://www.europeanrailtimetable.eu/rail-maps--guides-22-c.asp

Online, have a look at:

https://www.openrailwaymap.org/

But be aware that Openrailwaymap shows infrastructure, which includes lines where there are no passenger trains and lines with trains where the pass is not valid.

It really varies a lot between countries-in around half of those in the pass-scheme one can use all trains-as there are only the state-railways, in some others only a few minor branch lines are excluded-run by a local ´ćompany´ (that most often is not commercial at all) and in others you really have to select. F.e. in IT and ES are now also so called lo-cost alternative companies running trenes-on the same lines and between same stops as the national company-and these do not accept passes.

To travel from Zürich to St. Anton maybe a single ticket will be cheaper. Best to buy via oebb Website.