It looks like this thread hasn’t been touched in awhile, but I’m running into the same issue. The app worked perfectly on my Pixel but when I put it onto my Pixel 3, I can’t get the lessons to download. I’m logged in (have a subscription), connected to wi-fi, and when I click on a lesson to download, it says it’s download for a few minutes then gives me an error telling me there’s a network connectivity problem. I tried deleting and reinstalling and toggling the switch to allow downloading over data but nothing has worked. I generally do the lessons in the car on my commute so not having the app work on my phone means no practice for me recently. @chirojoe, did you ever get your app to work?
I’ve also posted about this over on IOS app, even though that’s about the iOS app.