from https://benefitsportal.eurail.com/benefits/german-youth-hostel-association/ 

International travellers holding a Eurail Pass valid for Germany can obtain free membership in the German Youth Hostel Association. The free membership card is your ticket to the 450 German youth hostels across the country.

The Link to the German hostel association about this deal does not work. I’m not sure if it works to get a member. You can write a email to the German Youth Hostel Association and ask about it. Please report about the response. 

The youth hostel is not free, but the membership should be free, which means the price is lower.

There are 2 types of hoStels-it varies really per country as to how many are 1 or 2.

The OLD style-mostly aimed at large youth groups, is Hostelling International. Is very big in UK, DE, Scandinavia (and also Australia and Japan) and less so in FR - IT and other countries. In the past you had to be a member of that-in your own country. Now no more, but you get lower price and sometimes a little more ´freebies´ by being member (I was for a very long time, and currently stay, but in private room in such a hostel in Helsinki/FI). It means that with a IR-pass they will consider you also as member without that card, but most certainly you canNOT sleep for free-and in DE they still have many petty rules and NO kitchens. This also holds for Swiss. (site: hihostels.com)

Private hoStels offer also cheap sleeps in multi-bed rooms, with usuallly also use of kitchen, sometimes even more free things, but this varies enormously. Many are in East--EUrope and close by main stations. You can find them on s site like hostelworld, most are also on booking.com, so its easy to compare. Its often cheaper to sleep there as in HI, but there are also often many complaints: dirty, unkempt, anything goes, no checks/controls etc. Some like that, others not so much. And some are great places with very friendly other travellers-in the right season- and loved by many. The ratings on booking are often a good indicator of that.

Hi Saraladrillo, I reported that the link is broken to my colleague in charge. As rvdborgt mentioned, only the membership is free, not the entire hostel stay. Cheers,

Hi, The link has been fixed. Cheers, Marion