Trashed: Procedurally Scattered Trash
Can I use this for any project?
Yes, feel free to use it on any project without having to do any accrediting.
I'm getting an error when I try to hide the trash assets collection, how do I fix this?
This just means that when the Trash asset was imported it didn't add it into the Scene Collection. To fix this just add the trash in again with the Scene Collection selected this time, or move the collections into the main Scene Collection.
How do I install this addon?
You can install Trashed anyway you could install any other addon. By going into Edit-Preferences-Addons and installing the downloaded ZIP file. Make sure you check the tickbox so it's enabled.