How install Qbittorrent on Debian?

[evilbunny]

Code:

               Depends: libqt5core5a (>= 5.8.0) but 5.7.1+dfsg-3+b1 is to be installed
               Depends: libqt5gui5 (>= 5.8.0) but 5.7.1+dfsg-3+b1 is to be installed
               Depends: libqt5network5 (>= 5.8.0) but 5.7.1+dfsg-3+b1 is to be installed
               Depends: libtorrent-rasterbar9 (>= 1.1.6+git20180215.01c41fadcf+patched-configure) but it is not going to be installed
E: Unable to correct problems, you have held broken packages.
rock64@rock64:~$

It looks like you half upgraded packages, and then decided to set the apt repository to an older version.

The quick fix would be to re-flash an image. Otherwise you need to downgrade/upgrade to a later version.