How should I use GnssLogger output with rtklib to compute the location?
rtklib (rekrcv) gets RTCM as input, and GnssLogger output is proprietary.
How do I connect these 2 tools?
Currently Rtklib does not support GNSS Logger data, but you could use Rokubun's Jason Positioning-as-a-Service online tool:
You can directly upload your GNSS logger file and the service will perform PPK. Also, when you download the results you will have the converted Rinex file, with which you can launch your own processes yourself.