Hi there,
go install will place the binary in the location specified by the GOBIN environment variable, which defaults to $GOPATH/bin, and GOPATH defaults to $HOME/go. So make sure these are properly set in your environment, and that $GOPATH/bin is part of your $PATH. If it’s setup correctly, which xk6 should give you the path of the executable.
That said, the error zsh: command not found: xk6 build is intriguing since it appears zsh interpreted xk6 build as a single command, which happens if you run the string "xk6 build". Otherwise the error would be command not found: xk6. Are you running xk6 from an IDE or a terminal that might be mangling the command?