I have a subscription to VpnOneClick, but everytime I try to download configuration it stops responding without modifying the configuration. VOC support say that it's a problem with my system, so does anyone know of a solution?

I am using a MacBook Air, with a 1.3 GHz Intel Core i5 Processor, 4 GB 1600 MHz DDR3 Memory, with 121 GB Flash Storage. The system is OS X Yosemite 10.10.5, and I'm assuming the most recent version of VpnOnceClick.

I didn't download this app from the AppStore, but I've already allowed it to make changes so I don't think that is the issue. It works fine until I click download configuration, but then as soon as I click it and it asks me to allow the changes it stops responding, and no matter how many times I allow the changes nothing happens and the app remains unresponsive, so I end up forcing it to quit and repeating the process. I've already restarted my laptop, once after 10 mins and another after a couple of hours. I've gone through my System Preferences looking for something that could make a difference, but I can't find anything that makes a difference.

Has anyone else faced this problem?