I got UART output (printf) working using minicom. Don't know what the difference between screen and minicom is but using minicom I set it to not use flowcontrol 115200 8N1 and it worked...
## GPIO Also, GPIO interrupt is working just fine. However, as @Maureen writes above, the PCR has not setup PTB22 as default. The pins are configured in an arduino style configuration as default: zephyr-project/arch/arm/soc/fsl_frdm_k64f/soc_config.c
So using these pins as input or output GPIO works just fine.
