The USB-Manager is for serial-ports only!!!
A DVBT stick is not a serial-port. It can receive AIS Signals as sound (SDR receiver).
OpenPlotter use the sound and sends it into a software to generate NMEA0183 sentences.
These sentences are send by network UDP 10110 to "kplex" a NMEA 0183 multiplexer software.
From kplex you can send it to a serial port if you wish.
It should directly work with opencpn on the raspberry.
A DVBT stick is not a serial-port. It can receive AIS Signals as sound (SDR receiver).
OpenPlotter use the sound and sends it into a software to generate NMEA0183 sentences.
These sentences are send by network UDP 10110 to "kplex" a NMEA 0183 multiplexer software.
From kplex you can send it to a serial port if you wish.
It should directly work with opencpn on the raspberry.