Schroth Autocontrol and Golf 2

Hello from Finland
Sorry for writing in english, I understand german but I cant write it

My question is (sorry again, I tried search, but didnt found):
I' m going to install Scroth Autocontroll II -belts into my Golf 2, and I'm going to use mounting point D:

But If I install them without backseat, do I need this adapter?

Thanks

Thank you, now I can save 16 euros :-4