Sure they are. To move your pass to another device, please contact customer service and mention when you want to travel.

I bought a mobile pass but discovered that I -unfortunately- can't run the app on my Iphone 6 (iOS 12.5). I contacted the customerservice but they appear to be busy. Meanwhile Ilike very much to travel (and use my pass) on Monday the 11th. Does anybody know a solution (better than buying a new smartphone)?. For instance printing my mobile pass or so?  

There is no way to print a mobile pass.

You need to get a smartphone where you can run the app.

You can’t print a mobile pass. Unfortunately it must be installed on a compatible phone. Do you not have any family friends with an old Android phone lying about unused? 

You don’t have to install a sim card or your whole life on it, just the interrail app which runs offline and just needs to be occasionally connected to wifi or hotspot from your main phone.

I don’t know about Netherlands but it is still possible to buy paper passes on the spot in some railway ticket offices, DB for example can still issue them. You would then have either to refund minus fee the mobile pass or use it later within 11 months of buying it if you get a compatible phone.

If you can’t get a paper pass easily you could possibly buy a cheap android phone from second hand store/ebay/mobile network selling pay-as-you-go cheap deal phone.

In the Netherlands, paper passes can be issued at the international ticket offices of Amsterdam Centraal and Schiphol.

Thank you so much! Knowing that I don't need to insert a simcard in a device to run the app is already useful; thank you.