Hi there,
Sorry to hear you're having problems. I have a few questions that might help get to the bottom of this:
1) Are you using a raspberry pi 3, or are you using a different r-pi with an external wifi module?
2) Are you connecting the raspberry pi to your internet router or your PC with the ethernet cable? You need to connect it to your internet router.
3) When you click 'Find Pi', do you get to the list of wifi connections? Or does it fail to find your connection.
4) Although I haven't tried it with Ubuntu (I generally use Raspbian), you should be able to connect manually. First, connect your r-pi to your wifi network (by selecting your wifi network and entering password on the r-pi itself). Then type 'ifconfig' into a terminal on your r-pi. Next to wlan0, you should see 'inet addr' (usually the second line). Next to that should be an IP address (usually 192.168.1.xxx, but sometimes it is different). If you open AtikAir on your PC, then press 'Set Remote IP' and enter that number, it should connect properly.
If you continue to have problems, email me at ChrisG@atik-cameras.com. And I'll see what I can do.
Chris.