Hello @jackie_YYY
Inside your FreeMASTER project you should use the serial communication for connecting to the running on target application.
Could you please check the following article (link)? It describes how to use FreeMASTER with MBDT for S32K3, providing details on the blocks functionalities, operating modes, and a demo example on how to inspect variables in your project.
Let us know if this helps,
Irina