Installing apps from desktop site "play.google.com/store" not working/slow
Have you checked that your device is recognized correctly? To do this, go to the Settings page and check the Last Used date. You may have multiple entries for the same device if you have switched ROMs or formatted the phone, and if you're trying to contact an old version of the phone, the install requests won't get to the device. If you have unnecessary entries here, you can hide them by unchecking the "Show in menus" checkbox.