This issue has been fixed. New packages are online now (we made a hot fix to the Unity Plugin, package names are appended with _2020-01-16.zip suffix).
The updated package also contains a new sample for spatial map localizing demonstration.
If you want to fix the problem with the old package, just change line 57 of Assets/EasyAR/Scripts/Utility/FileUtil.cs: path -> PathToUrl(path)