So I downloaded the tutorial to try out some stuff but I keep getting errors in both the 2019 and 2020 versions. Anyone know why? - thanks
Assets_Project\TutorialInfo\Scripts\Readme.cs(4,14): error CS0101: The namespace ‘’ already contains a definition for ‘Readme’
Assets_Project\TutorialInfo\Scripts\Readme.cs(11,3): error CS0579: Duplicate ‘Serializable’ attribute
Seems like your Readme.css class already exists within your project. Not sure how this is related to the Animation Rigging package but I would put Readme.css in a namespace of its own to avoid name clashes.
The problem is that it seems like several resources get info from the Readme.cs. I am not sure if your solution will fix this - not even sure how to do as you state 
I’ll have to look it up. Thanks for the reply!
More info on namespaces:
The Readme.css class is in your TutorialInfo folder, so I would make sure every scripts contained in that folder has its own namespace to avoid conflicts.
Also, not sure about this error:
Assets_Project\TutorialInfo\Scripts\Readme.cs(11,3): error CS0579: Duplicate ‘Serializable’ attribute
Do you have the [Serializable] attribute twice on top of your Readme.cs class?
I’m sorry for conjuring this post, but deleting the Unity folder in that project will help you out. danUnity is right. There are 2 Readme.cs files in the project, so we’ll need to delete one. I’m assuming you’re trying out the big worm project. If you were, the Unity folder doesn’t look like it has anything dependent on it, so deleting it works fine for me, tho it does drop warnings, but so far things look fine.