I'm having the same issue, except I am only trying to install the Realtek ALC 898 audio driver in my newly performed Sierra 10.12.4 install. Per the stickied post, I performed my other multibeast kext installs first, restarted, and now only my Realtek ALC898 audio driver remains - but Multibeast keeps failing, with this error message in the log.
06/24/17 16:31:39 - Starting MultiBeast 9.1.0-20170501
06/24/17 16:31:48 - Failed to find node with path 'Drivers > Audio > Realtek ALCxxx > Optional HD 4600 HDMI Audio'
06/24/17 16:32:09 - Mounting EFI
06/24/17 16:32:09 - Installing 'Drivers > Audio > Realtek ALCxxx > ALC898'
06/24/17 16:32:19 - Install of '/Users/drew/Downloads/MultiBeast.app/Contents/Resources/Clover-ALC898.pkg' failed.
'installer: Package name is Clover ALC898
installer: Upgrading at base path /
installer: The upgrade failed (The Installer encountered an error that caused the installation to fail. Contact the software manufacturer for assistance.)
'. Exiting.
zangjiatao - your EFI partition is not mounted. Run Terminal, type in 'diskutil list,' and then mount the relevant EFI partition. There are plenty of guides out there to mounting, use those for reference.