After looking at the manual for this device it is a rather strange method of setting it up.
The device actually starts out functioning like a router. You connect to is via its own wifi name and then put in the 192.168.4.1 ip address. It is completely seperate from your home network at this time. I suspect it has its own dhcp server and gives your pc a ip address in the 192.168.4.x range.
What you then do is configure it to use the real wifi network in your house. Although the manual does not explain I suspect it will change its IP address to use one it obtains from your router. It then seems to connect to the companies web site and it appears you control it via their web site rather than directly access it.
This is a extremely scary device when they do not clearly document how this works. I suspect it will function if you follow their instructions and be the dumb consumer who does not question technical things.
My concerns would be.
After it is running does it leave its own wifi network up, can someone connect to this network since it does not have any security.
Do they disable the the 192.168.4.x network and the dhcp server.
Since this device appears to allow access from the internet can someone compromise the device and then hack your network. All kinds of security cameras have been hacked.
I suspect it will work by "magic" if you follow their instructions, you do not need to change your router. From the little they document it appears this device can only really be used via the internet, it does not appear you connect to it directly or on your home network other than the intial setup. If there is no way to run this device without a internet connection maybe it is best to toss it the trash and find one that is more secure.