Oh dear that sounds complicated. If anyone wants to remotely control my laptop and do it for me I would be very grateful. Not sure what I can offer in return.
The full instructions.
Download the ZIP File from MediaFire.
Open the downloaded file with 7-ZIP.
Click on the button "extract" and extract it to the Desktop by clicking the '...' button.
Close 7-ZIP and go to the Desktop.
You'll see two files "mb_LinkSysVolume.dll" and "CoreAudioApi.dll"
Right click each file one at at time click on "Copy"
Open the folder "C:\Program Files (x86)\MusicBee\Plugins" or wherever MusicBee is installed too.
Right Click, Paste each file into that folder.
It will ask you "Do you want to run with elevated privileges to copy." Say YES
You should end up with
both files in the plugin folder.
Start MusicBee. Click Edit > Preferences > Plugins.
You'll see "mb system volume link"; It should be enabled automatically, if it is not click "enable" and
restart musicbeeOtherwise, click on "Configure" and simply click 'Sync Volume'. I assume you'll want this automatically on MusicBee startup so click the checkbox.
If your still having trouble after following that, send me a PM with skype/teamviewer and I'll do it (attempt to do it first tho

)
#edit After completing the steps, you can delete the files from the desktop.