Thanks very much, but the photo above is from Firefox, which never was the problem.
For log-in users the player (Chrome) does not work well and presents those numbers at the end of each song.
Tried downloading the file for ten times.
Five times via the direct link to the file: works fine.
Four times via the download link from Download Manager: download terminates after 70-90%.
I also initiated both downloads at the same time and the result is the same. Direct link to the zip file works fine, the Download Manager link stops downloading and the result is a corrupted zip archive.