@EDE  you can use your paper pass also without link it to the app, write every train down on the list provided. 

If you want to link it to the app than visit this tutorial page or get in touch with customer service.

I am having the same issue…..have reservations but only giving me the option to link to a paper pass from within the mobile app.  My app is up to date.  Have wasted 4 hours on this during my vacation today.  Why only give the option of paper on a mobile platform????

Sorry I don’t understand your question. You don’t have to link reservations to the app. 

If you mean that you get a Reservation via postal mail on paper, this happens on some trains like Barcelona-Paris/Lyon. 

Can you please give us more Information about route, date and screenshots about the problems that you get, so we can help you. 

Eurail pass is a waste of time and money. I was not able to use it due to not having been provided paper/cover pass number. I lost two first class passes. Customer service basically admitted that it was their fault but did not return the money. Instead they offered me to buy more passes from them, pay the return fee, and then they may add additional days to the new passes. Thank you, but no thank you. I am back from my trip. Had to buy tickets and seat reservations  from the railway station instead. Took  about a month for the customer service to respond, I was back from my trip by then. Fraudulent service. Save your money. We all need to start the group law suit against eurail selling unusable passes. 

 @Stacy Reves Sandate 

Have you bought a mobile passe or a paper pass?

If you have a mobile pass you got your pass number in the confirmation mail. The pass number is also available on the order overview in your Interrail/Eurail account.

I bought mobile passes. And yes, I received the passes’ numbers in email, put them into the app, but that was not enough - the app was asking for Paper passes numbers, I know, this situation is as dumb as it can be. I just gave up and said goodbye to the money lost, over $700 USD. 

The customer service will politely ask you for mire info, more screenshots, etc. as if they are trying to help you, until they finally exhaust you and you will be happy to just let go of the problem by stopping communicating with them. No solution to the problem. We all need to team up - any lawyers there? The app is a scam.