Train from Paris to Mannheim in Germany

I will be travelling from Paris to Mannheim on may 10th, but I am finding it a bit difficult to make a reservation. I got into this link for the DB ( see below) and found that I can make reservation for the train I want for €5.20, which is much cheaper than the €20 reservation through the local trains in France that would take me to Strasbourg. I made the reservation in the DB site and got an email with my seat and car, but there is no bar code or QR code or even nothing that states my name, so I cancelled that reservation. I wonder if someone can help me if reservations through that DB site are ok, or if there is a better way to reserve that would not give me trouble while traveling! 

Thanks a lot!

https://int.bahn.de/en/buchung/fahrplan/suche#sts=false&so=Paris%20Est&zo=Mannheim%20Hbf&kl=2&r=13:16:KLASSENLOS:1&soid=A%3D1%40O%3DParis%20Est%40X%3D2359120%40Y%3D48876976%40U%3D80%40L%3D8700011%40B%3D1%40p%3D1744661048%40i%3DU%C3%97008711300%40&zoid=A%3D1%40O%3DMannheim%20Hbf%40X%3D8468917%40Y%3D49479352%40U%3D80%40L%3D8000244%40B%3D1%40p%3D1742845592%40i%3DU%C3%97008014008%40&sot=ST&zot=ST&soei=8700011&zoei=8000244&hd=2025-05-10T06:45:10&hza=D&hz=%5B%5D&ar=true&s=true&d=false&vm=00,01,02&fm=false&bp=false&dlt=false&dltv=false