If you have problems installing the latest version of MNTN on Mac OS High Sierra, it is likely that it has to do with system security and privacy settings. To solve this problem, go to your Mac's system preferences, and there click on security and privacy. Make sure that the settings allow for apps downloaded from App Store and identified developers, as shown below.
Another way is to uncheck SoundFlower in the MNTN installer menu. You might need to look twice to find the button, but it’s there!