Installing the Media Module + WYSIWYG Module on Acquia Cloud
Short answer: turn off livedev in your Acquia Cloud dev environment.

Longer Answer: I was trying to drush my modules and do basic site building in their environment using the livedev option. But they don't let you run mkdir and scp live in their environment via CLI.

Their recommended workflow will have you add your modules/libraries locally, commit via git and then push up to their environment.