Here's my solution for a critical error i encountered and solved with Anthony's help.

When you are importing Level Designer 2.0.2 (november 2021) into Unity for the first time you may run into a critical error that prevents you from using the plugin:

"Multiple precompiled assemblies with the same name Newtonsoft.Json.dll included on the current platform. Only one assembly with the same name is allowed per platform. 
(*ProjectFolder*/Library/PackageCache/com.unity.nuget.newtonsoft-json@2.0.0/Runtime/Newtonsoft.Json.dll)"

Here is a solution from Anthony:

For Unity 2020+ you have to remove “Version Control” or “Unity Collab” package, to have their newtonsoft package removed. Or you can remove the newtonsoft dll from the Exoa/Commons/ folder, but you may have loading/saving issues on some devices.

I tested it an hour ago on Unity 2021.2.5f1, error appeared and went away after removing Unity Collab package.
Thank you for replying to my mail back in November, Anthony. Hoping you would update the plugin soon.