1/ This module doesn't work with M5stack Core2 & AWS. Some GPIO pins are already in use. Haven't found that info clearly stated in the documentation or in the M5 shop. Maybe I missed it ?? It works well with Core1. But it's not easy to guess because it's a new module (august 2020).

2/ Till you connect the StepMotor Driver it becomes impossible to reload a program by pressing "run" in UIFlow a second time. You need to reset the core1 each time you want to send your program again from UIFlow.
3/ Don't set the freq to 0 or the rest of your program will fail silently... Set it to 1 instead if needed.

4/ Can't succeed to pilot the 2 motors individually with the dedicated UIFlow blocks. When we use the Set single motor X state 1 and 2 motor are attached (say on X and Y), both start and stop at the same time. Same if you use Set single motor Y state 1 ... We get around this bug by using the Hardwares>PWM fonctions this way :

Please notice that we use the PWM module with the 2 Core1 timers (0 and 3) and that our workaround will not work if you need to control 3 motors...

A very tiring experience ! It would be great if the documentation be more explicit and that this module and UIFlow functions works a little "more" I would say.
But at the end it works.