Version 1.0.1-1.0.0 of the Unity plugin fixes the 64-bit issue, so the workaround is not needed anymore.
about 5 years ago
With the current version of the Wikitude Unity Plugin (1.0.0) there is a known issue when running it on an Android 64 bit phone. This issue will be fixed in the next Unity release, what you can do for now is the following:
Change the file extension of the aar file under Assets/Plugins/Android from ".aar" to ".zip" and extract it
Delete the folder lib/arm64-v8a
If your archiving tool created a new folder when extracting, zip only the contents of this folder and now rename the extension of the file from ".zip" to ".aar"