On MacOS 10.13 machines, Soundflower Kext needs to be installed before you can stream sound from a MacOS 10.13 machine to your device. This is a new security feature introduced by Apple.
The Allow button, to complete the Soundflower install, is under the menu System Preference / Security & Privacy / General tab.
However, if you try to click the Allow button in a remote session, such as, a Splashtop remote session or LogMeIn remote session, the click will not register. Clicking on the Allow button is not registered through a remote session to install any drivers - Splashtop or others.
This is also by design from Apple for security. Some one at the physical Mac computer needs to click on the Allow button.
Note: Even without the Soundflower loaded, the installation is still complete - just no audio streaming support.