Make sure the toolchain of choice is installed on your system.
For example, to install the aarch64-unknown-linux-gnu toolchain, run:
brew tap messense/macos-cross-toolchains
brew install aarch64-unknown-linux-gnu- aarch64-unknown-linux-gnu
- aarch64-unknown-linux-musl
- arm-unknown-linux-gnueabi
- arm-unknown-linux-gnueabihf
- arm-unknown-linux-musleabihf
- armv7-unknown-linux-gnueabihf
- armv7-unknown-linux-musleabihf
- i686-unknown-linux-gnu
- i686-unknown-linux-musl
- mipsel-unknown-linux-gnu
- x86_64-unknown-linux-gnu
- x86_64-unknown-linux-musl