Our Android application supports Android 2.2 (Froyo) and newer, although some features won't be available on all platforms. In particular, you'll need Android 4+ (Ice Cream Sandwich) to turn your device into a photo frame automatically using Android's Daydream feature (older devices will need to start Photo Stream manually).
We recommend that you install the application directly from us, if your phone manufacturer allows that (some don't, some do but you'll need to modify settings). If that's not an option, the application is also available directly from Google
Find a bug? Please report them at our bug tracker.