Missing ECTS requirements, still trying to apply, should I mention it on my motivation letter?
Call them beforehand by phone and ask if you are formally allowed to apply if you are missing the credits and explain your situation. There is not much point for a full application if already the admin people would put it on the "no" stack without a real decision maker even seening it. 
If you get a "go ahead" via phone then state this fact in your letter.