When I launch Sage 50 a window opens and displays: Bad Key file

SOLVED

I followed all the steps normally.
at the end when I launch Sage 50. a window opens and displays: Bad Key file
then this puts me this product not properly install
  - I resumed the process several
- I have to deactivate my anti-virus
  - I disable all firewalls
   - restart my computer
  - use the StudentVersCleanUp
it always puts me missing one of the files

What should I do and I have course and exercises to do