Upon first connection the OctoPrint Wizard will guide you through the required steps, including the configuration of your printer profile.
It might happen that during the first boot OctoPrint fails to detect the correct port speed, hence fails to connect. Before connecting make sure to select manually the baudrate of 250000.
In case of any error OctoPrint default behaviour is to disconnect from the printer. This setting can cause a deadlock when the Klipper firmware goes into shutdown due to configuration errors or, for example, bad thermistor connection (i.e. ADC out of range). The shutdown state cannot be cleared because the FIRMARE RESTART button is not active when disconnected. To avoid the deadlock go into Settings > Serial Connection > Behaviour > Error Handling and set it to Cancel any ongoing prints but stay connected