Dear Henry,
the SLN-PRK-NODE is not directly supported by MCUXpresso SDK nor by out-of-box FreeMASTER demos. Please get the examples for the FRDM-K64F board at the MCUXpresso SDK Builder home page and adapt it to your board's Serial or USB connection.
Alternatively, you should be able to connect FreeMASTER to your board using CMSIS-DAP communication and access the MCU memory directly. In this case, there is no communication driver needed in the target MCU application. You will only need to load the target application ELF to FreeMASTER so it knows the variable addresses. Refer to FreeMASTER user guide for more details.
In order to connect using CMSIS-DAP interface, use the FreeMASTER Connection Wizard as outlined in the picture below:
Best regards,
Michal