This app doesn't work on Xiaomi(Realme, OPPO, Vivo).

Miui OS prevents apps from running in the background.
Turn on auto start for SMS Forwarder.

 

Solution 1

1. Open the Security icon on your device.

 

2. Tap "Manage Apps".

 

3. Tap "Permissions".

 

4. Tap "Background autostart".

 

5. Tap the slider on the right side to enable Auto Start for SMS Forwarder.

 

6. The Auto Start option must be turned on.

 

Solution 2