We use Collector Classic to collect data over a large area in central AZ. Users with Android phones are reporting very long/never-ending download times when they need to download the map (because of a change in the map, a new user logging in for the 1st time, a new phone, etc.).
I've had the same experience personally. The only way I've gotten around it, i.e., gotten the map to download, was to restrict my work area to a small portion of the overall study area. Then the download completes quickly and the app works fine.
Once a map is downloaded, the app works fine and sync goes smoothly. I should note that although we've used Collector for this work for 18 months, the problem has arisen only in the last 3 - 4 months. Also, we're collecting data steadily so now the full extent of the map has ~6000 points and hundreds of polys. Could we be suffering "data overload" in the downloading process?
Does anyone know what might cause this problem and how to deal with it?