Hello @wiktork,
Starting with the MBDT for S32K1xx 4.3.0 we have added support for the MC33771C and MC33772C alongside some examples, so please update your current MBDT toolbox installation with the new one, so that you can use the new blocks for your BMS application.

For the FreeMaster issue, it looks that the FreeMaster application cannot connect to the board. This might happen due to multiple reasons like miss matched UART configuration, pins not assigned correctly for the UART or your application might not run as expected on the board. My suggestion is to update the toolbox and start from one of our BMS examples, which uses also the FreeMaster block so that you could see the measured values on the display.
Hope this helps,
Marius