Crossgrade Procedure

I am buying among other things Cubase Pro 11 crossgrade from Thomman. Where do I put the proof of eligibility? Where is the submission link? Do I have to do that before purchase or after? Is there a guide in the box?
Why is this not properly explained on Steinberg website?


Well, if you are purchasing at Thomann, you will have to ask Thomann how to submit the proof.

I can tell you that on Steinberg store, I added cossgrade to basket and checked out. No money was taken but I got message to upload screenshots of serial numbers of other DAW.
I got an email today from Steinberg saying they received my proof and it may take time to process.

I guess you should call Thomann?

Problem solved. Thanks for help.