Hi Scott,
Here’s a link to the APK and obb files I’ve used:
https://drive.google.com/folderview?id=1JFKo-buDh94eGYWs8L1DNJdCzpLOjGZL
Firstly, install the app. Then create the directory for the obb file.
The easiest method is to use a file manager app like ES File Explorer.
Under /home/Android/obb create a new directory named “com.zwift.zwiftgame” and paste the obb file in there.
Launch the app. If it craps out first time, exit and launch it again.