Double check if the the battery is charged. If you do not see your Cycloop device on list, tap rescan. If needed, perform that several times. If you see an error message at the bottom, the first thing to do is to restart the Bluetooth on your phone (switch it off and back on), and try to pair again.
Additionally, if you do not see the device in the "Choose Your Cycloop" tab, try to clean cache and data:
1. Open Settings menu in your phone.
2. Find Monimoto App in the menu, then locate the app.
3. Tap on Storage and clear the data.
If you are unable to setup the tracker in the App setup process, check your phone's bluetooth list to make sure any devices labelled mm.XXXXXXXXXXXX are unpaired and forgotten using the little 'i' button. Then try the App setup process again.