I found a cable that I purchased earlier for my phone, and can confirm that it works with the Max 2 - I tested both a USB stick and a USB keyboard.
EDIT: A USB mouse works as well - just slow on the screen.
The adapter that I have as a small USB HUB included - that does NOT work - as soon as I connect more than one device, the MAX 2 crashes and need to be rebooted.
/Jan