Apple introduces a new security feature that requires user approval before loading new third-party extensions on a macOS 10.13 machine. Therefore, you might need to approve the loading of Soundflower Kext before you can stream sound from a macOS device to your device.
How to approve the loading of Sound flower
1. After installing the streamer on a macOS 10.13 device, the system will pop up a warning.
2. Go to System Preferences / Security & Privacy / General tab, click the Allow button on option System software from developer "Splashtop Inc." was blocked from loading. The allow button might be blocked, please remember unlocking then click the allow button.
Please note that the option to allow loading is only available for 30 minutes after the System Extention Blocked warning popped.
3. That's it! If you don't allow the loading, you will get another warning in couple minutes.
What if I missed the 30 minutes timer to load Soundflower kext?
1. Open Terminal, run command: sudo kextload -- /System/Library/Extensions/Soundflower.kext/
2. Go to System Preferences / Security & Privacy / General tab, follow above instructions to allow the loading.
You only need to load Soundflower to stream sound when first-time installing the streamer on a new macOS 10.13 device. You don't need to load Soundflower in below cases:
1. You have the streamer installed on an older version of macOS, then upgrade macOS to 10.13.
2. You have approved once before on your macOS 10.13 device.