Make sure when installed you give access to Bluetooth and Camera.

If you fail or missed the permission to access Bluetooth or Camera you can do it later 

on iPhone

• Setting -> Tachosafe -> Camera/Bluetooth or
• Setting -> Privacy -> Camera/Bluetooth

on Android

• Settings -> Apps -> Manage apps -> Tachosafe -> App permissions or
• Settings -> Apps -> Permission manager -> Camera/Bluetooth -> Tachosafe or
• Settings -> Apps -> Apps -> Tachosafe -> Permissions -> Camera/Bluetooth or
• Settings -> Apps -> Tachosafe ->Permissions -> Camera/Bluetooth or
• Settings -> Apps & notifications -> Advanced -> Permission manager ->Camera/Bluetooth