
If you have to enter a pin use 0000 or something else. Click on the message and follow the steps.
After first print it will ask you to setup the printer ("MTP-2" for me). You should now be able to print to a new printer ("POS58 Printer" in my case). Now select these ports in the printer installation and repeat installation for the second port (not sure if necessary). In "COM Ports" tab you can see the COM ports being used by the printer. Enter "Bluetooth" in search bar and select "Change Bluetooth Settings".
Open the Control Panel (the old one, not the new Settings menu).
Install the driver and select Serial Port (COM Port) during installation.
Pair the printer with Windows (for me it is visible as "MTP-2" with error "Driver is unavailable"). If the printer has Bluetooth but doesn't support BT printing with Windows, try the following: This is a copy of the driver CD included with the following GOOJPRT printers: Printer Driver and Apps for GOOJPRT Thermal Printer - Version 6.33 from 2019.