Usually you can choose between paper and mobile pass. Don’t know how it is with the Discover EU passes. 
InterRail tries unfortunately everything to push the sale of mobile passes and hides the paper passes as good as possible. Seems they don’t understand that some people like to have paper tickets as memory from their trips. This year would be 50 years InterRail but it seems there is not even a special design this year for the paper pass envelope. In 2012 for 40 years they had a special design.

Maybe in a few years they won’t sell any paper passes if they continue like this…. 

Keeping my fingers crossed that you will be able to get a paper pass!

I don't know how the free passes will be provided. If it's through a discount code that can be used on the Interrail order website, then I suppose you have the choice between the mobile and paper pass.

You get the mobile version (7 days in 1 month global pass) for #DiscoverEU. But please ask directly for more information the #DiscoverEU Staff via mail or in the Offical Facebook Group #DiscoverEU Official. 

@souvenir: alas, in fact the first 40 yrs or so of the IR-pass-offer there was a demand to bring back the booklet with all your trips written in. As is explained quite a few times here (and this is now solved with this new online app pass); as places of sale of the passes are quite different from the countries of use, all noted trips are in fact roughly counted and after the income is divided up over all the 99+ different train companies that participate in this scheme.

Gradually fewer and fewer people did that-bring back the booklet.THey finally got the message and you could ask for it to be sent back-with a small present (last time I did this it was a USB-stick with IR-logo).

Besides this, also most traincompanies themselves push for more and more online ticketing and less and less paper. Several economizing traincompanies do not even sell IR anymore or only the app and not the paper.