I really enjoyed it, the voice acting was perfect, and the music and art really suit the poems narrative.
Yeah I also changed from combined to diffuse colour only to make it work correctly, I think 2.9 is different again from 2.8.
Using 2.9 certainly had a few extra challenges in this tutorial. :)
This video should help you baking AO onto colour in Blender 2.8+It uses the same process of mixRGB of a texture(image ) and AO map, then bakes it into a single texture(image). Could be helpful for you.
Youtube - Short Video On Baking AO/Colour 2.8+
