This page details the necessary steps to take, in case you experience an error while installing the Customify Pro Addon.
Please be aware that the Pro version is an add-on plugin, which adds the additional pro features to the base theme.
You therefore have to install the Pro version as a plugin, not as a theme. To upload a plugin zip, navigate to Plugins > Add New > Upload Plugin from the WordPress dashboard.
See this video:
After you have installed and activated the Pro version plugin, you can go to Appearance -> Customify Options to control all Customify Pro modules.