Why does this error occur?,What does this error mean?

Questions & Answers
1

I am a Unity beginner, I have just imported Book of the dead and TextMeshPro and I made a simple terrain in my project too, I have not edited any code or assets but when I play/start the project, 452 errors appear and most of them say:

“The type or namespace name ‘XXX<>’ could not be found (are you missing a using directive or an assembly reference?)”
What does this mean and how do I fix it.
Thank you,I imported Book of the dead assets in and TextMeshPro and thats it, and I’ve also made a small terrain but when I go to start my project 452 errors appear and most of them seem to be “The type or namespace name ‘ChangeEvent<>’ could not be found (are you missing a using directive or an assembly reference?)”
What does this mean? Why does it do this and how do I fix it. I havn’t edited any of the code or assets It’s just how it was when I imported BoTD: Environment. I am a beginner on Unity and I just want to make a simple terrain.

2

From what I remember, that one can conflict with built in packages. Make sure you are importing ONLY Book of the Dead into a new, empty 3D project. Try that first, before importing anything else.