If you use iOS but not the Home app, you can follow the below steps to add the HomeKit-compatible device to the Meross app:

1. Reset the smart device according to the user manual.

2. Keep the smart device in that mode for at least 15 minutes.

3. Open the Meross app-> tap the + button on the home page-> select your device model-> select the Non-HomeKit version to continue. For some model that doesn’t have the Non-HomeKit entrance, you can choose any other ones from the device list (such as the MSS110 or MSS210 smart plug).