As you see this module is somewhat of a "Maker" version with exposed PCB. To make it easier to test I soldered the screw terminals:
Documentation on how to use that module was found using a QR-Code on the package that points to the related mobile app eWeLink
Jumper configuration on this module is critical or you will fry it...
I opted for the default mode and connected a 9v DC power supply to the input. Pairing it was not as easy as it seemed and took me a few tries and only works on 2.4GHz wifi. After that I could turn on and off the relay using the eWeLink app.
I was also able to add the control to GoogleHome on my Android phone, but note that it required you to sign-in and have an account at eWeLink so you might want to check your security and isolate the device on a separate VLAN or something.
One thing I was not able to get to work is voice activation through either my phone or via my GoogleHomeMini. I do have an other Wifi switch that I bought at Walmart that works, but could not get that one to work the same way. I'll probably try again at a later time.