Hey sg.lee, welcome to the Fuse Forums. In order to use Fuse with 64bit support, you have to install latest Fuselibs and Uno which now in ver 1.12.x. There are many ways to install, but the most simple one is using fuse-sdk npm package by @mortend. Check out his Medium blog for more information here
After you install the latest Uno, you can build your project using uno build android in the command line. The default preference is that the output APK is arm64-v8a when in debug mode and if you run using uno build android -c release it will release a fat binary ( ‘armeabi-v7a’ and arm64-v8a inside the APK). More info on the forums here
Hope it helps