You could drop Plug even with the existing stable release. Native packages have been supported since Vim8 and NeoVim 0.2

The cat command is unnecessary when all you want to do is copy a file's contents to clipboard. Just do

  pbcopy < my.txt

The Steam client has been updated to 64 bit quite a long while before. But the in built updater seems to only fetch the 32 bit version. If you uninstall Steam and do a clean reinstall from Steam website, you will get the 64 bit client.