I tried installing this through the workshop but didn't work so I decided to comb through my workshop files and found the folder for this mod and read the read.me file. the read.me file.

the instructions are the following:

Step #1: Extract the SME4M2 folder from the archive.
It is not advised to leave the plugin in the .zip archive, as the music is already compressed with the Opus encoding format.

The music is encoded into segments of 48000kHz 128kbps OGG Opus-format audio.
Aleph One comes with the ability to decode and play the music. To play the music outside of the game, make sure that your music program can decode Opus files.

Step #2: Place the SME4M2 folder into the /Plugins/ folder of your Marathon 2 installation. If you are running standalone Aleph One on Windows, it's a good idea to install Marathon 2 inside the /AlephOne/ folder in your /My Documents/ folder.
This keeps all of your Marathon files in one place, maintains backwards compatability, and allows you to run a single barebones Aleph One engine for all third party scenarios, as well as a general /Plugins/ folder that applies for all titles.

If you are running the Steam version of Marathon 2,
then Marathon 2 should be installed in your /steamapps/common/Classic Marathon 2/ folder.
This procedure should be analogous for Mac and Linux, but if issues arise, I cannot assist you.

Step #3: At the main menu, select 'Preferences', then select 'Plugins',
and verify that no other active plugins are labeled "Solo Lua".
Aleph One cannot run more than one Solo Lua script at the same time.
When Solo Lua is running, achievements are disabled.
This is unfortunate, but the Solar Soundtrack for M2's dynamic music system cannot
function without Lua code.
At 'Preferences', if you select 'Environment',
you can verify that 'Use Solo Script' is disabled, as this will override plugins.

Step #4: At 'Preferences, select 'Sound', and adjust the 'Music Volume' to your tastes.
By default, Aleph One sets 'Music Volume' to 40.
The intentional experience for the Solar Soundtrack for M2 is a 'Master Volume' of
80 and a 'Music Volume' of 100.

There is not a single audio segment that is mastered below -22 LUFS integrated,
and some segments can break -9 LUFS short-term and peak at 0.0dB! Talk about dynamics!

If you feel that M2's atmospheric sound effects interrupt the music,
then feel free to uncheck 'Ambient Sounds' or 'More Sounds'.

remember to uncheck solo script, that tripped me up lol