not recognizing arm64. · Issue #579 · Medium/phantomjs
https://github.com/Medium/phantomjs/issues/579
Unexpected platform or architecture: linux/arm64Phantomjs doesn't has arm64 support. Need to rebuild it manually.
It seems there is no binary available for your platform/architecture
Try to install PhantomJS globally
Build | PhantomJS
http://phantomjs.org/build.html