Currently CUE can only be installed from source.
Go 1.10 or higher (see below)
To download and install the cue
command line tool run
go get -u cuelang.org/go/cmd/cue
And make sure the install directory is in your path.
To also download the API and documentation, run
go get -u cuelang.org/go/cue
You can load the binary for Windows, MacOS X, and Linux at https://golang.org/dl/. If you use a different OS you can install Go from source.
Follow the instructions at https://golang.org/doc/install#install. Make sure the go binary is in your path. CUE uses Go modules, so there is no need to set up a GOPATH.