EasyAR SDK 2.3.0/2.2.1 have been released. They are compatible with Unity 2018. You can get it from EasyAR website. You may need to refresh the webpage if you didn't see them.
Additional For MacOS, because Unity 2018 use Metal by default, you may also need to change the settings to use OpenGL Core. Look at Unity title bar and make sure there is OpenGL instead of Metal.
BTW, we are working on a perfect solution in EasyAR SDK 3.0, which will use the most of Unity features instead of a custom renderer. We will make the whole EasyAR Unity Plugin open source.