When you get them through the ecosystem the .cs files are installed in a Playmaker Custom Actions folder iirc and then Unity recompiles all of it since you added an asset. It might be cleaner to import the file from within Unity by using the import function in the Projects tab.
Each script has its namespace, plus its own identity too where the class is named like the script, and in most cases for custom actions a category too although developers sometimes are not careful enough with this.
So look at the script's first lines and see if there is a category attribute, it might be a good thing to create a subfolder that has the same name and put the script in it. Some of these folders have the names of the official categories btw.
