Hey @hsam,
This error can happen on Linux if journalbeat is built without cgo, though in your case it seems that you are compiling with cgo enabled 
Could you try to build journalbeat with this command?
PLATFORMS="+all linux/arm64" mage crossBuild
If this command works you will find the results in build/golang-crossbuild.
You can build whole packages with the following command:
PLATFORMS="+all linux/arm64" mage package
Built packages can be found in build/distributions.
You may also find more information in this thread: File/Packet/Metric beat on Raspi Centos 7 (armhf/armv7l)