Hi Blumenkraft, I simply followed the hint above from seven.of.nine. I’ll try your advice in the next days.
As a newcomer to SailfishOS it isn’t easy to find the best “How-to’s” or instructions.
A correct installation of microG seems to be important for other newcomers, too. Perhaps it could be mentioned here Beginner or at another prominent place, where newcommers can find it more easily :-).