When I started this thread, I had encountered "access blocked" without having downloaded anything in the previous days. That´s why I was so shocked and interpreted the hint on Nops page as "the map in lo longer useable, online and offline".
Now it seems that it is still available online - maybe I had a cache bug.
Yesterday, I even downloaded 109 tiles via Locus.
Then, after moving around the map a little, "access" blocked" appeared again. Today the online map is available again. I won´t download anything.
Other maps are ok, I use them for comparison/double-checking, but they don´t show the official trail markings - this feels a little like suggesting "get a cat" to a dog owner...

I will get the unlock key.