So guys it worked, thank you for your help. I think the problem was that I didn't had enough disc space for the subsequent activation (yeah not enough disk space you read this correctly!!!). Since I am using an SDD as primary harddisk it does not have too much space on it. The first tries I just calculated enough space for FL, FLMM and the Installation of CF, but I had not enough space for the activation of CF (I just didn't thought that it would need another 6gb space).
So I am stupid, but I think this was the problem for me
Thank you again for your help!!