I was following the Meraki documentation where I first made a mistake but now it saw my error and fixed it!
So if you know the IP of the host you wish to track.
Go into Organization -> Settings and NOT Network -> General, that was my mistake btw 😛
There you need to add a custom PIE chart.
There you fill in the desired name of the application and choose IP range.... and then fill in just the IP of the host.
Once that is saved you will find the application under custom in the add webapp dialog.