If you are using Android 10, we would suggest taking the following steps, and then looking up the information for your specific phone.
- Go to Settings on your phone
- Go to Location then to App Permission
- Select Zombies, Run!
- Set to 'Allow all the time'
It should be noted, we do not actually access your location unless a mission is actively being run. However, this setting allows the app to keep using your GPS while the phone screen is switched off or in the background.