Smush Pro won't install due to 'permissions'.

I keep trying to install Smush Pro and it keeps telling me that my permissions are wrong on the WP-Contents folder. I checked. There's nothing wrong with the permissions. I've cleared the cache. Everything is up-to-date. Still, no dice.

I thought perhaps it was because my login was cloaked, so I disabled the plugin. Cleared cache. And still will not install.