I got it working but it wasn't in the instructions.

[rgkirch]

Hey! I got things working and I wanted to share one place where I got stuck.
This page was the most helpful but I never get the [ 2401.458834] cdc_acm 1-1:1.1: ttyACM0: USB ACM device dmesg output like in the example. I also don't see any change in /dev/ttyACM* or /dev/ttyS* when attaching or detaching. It didn't show up in adb devices until I ran sudo adb kill-server and sudo adb start-server and then it worked.
https://gist.github.com/rgkirch/c033d1948e290e30329f6f43a85da11a
Thanks!