Toxe Ok after some digging I found out how to get the correct directory regardless of where somebody stores steam on their device. But I have one last problem:
When printing the applications file path (Which should be the games steam installation folder)

On windows it works great, however because of how Mac works, I get this result:

Now the bit I highlighted in red is the part that I DONT want. I just want to get to common/Plethora as this is the installation folder. (I also don't need plethora.app)
So to work backwards I tried to add on ../MacOS../Contents../Plethora.app../Plethora/userdata/ to the end but this didn't work.
To sum up, I just need to get to the common/Plethora folder somehow through this directory. Maybe some way to get the parenting files and work my way to the installation folder as I have everything here that I need.