Zwift hängt sich nach dem Starten sofort auf

From the log file snippet above it looks like you enter the pairing screen, and then the program exits.

Do you use ANT+ or BLE (Bluetooth)? If the latter, try to install vc_redistx64.exe (it is probably in the %programfiles(x86)%\zwift folder or can be downloaded – see link here: Zwift PC Bluetooth issues - #95 by M.Milner

If that doesn’t help I recommend you contact Zwift Support with your problem.