I am trying to get Protractor up and running following the official Getting Started Guide.
The command
webdriver-manager start
seem
I ran into the same issue when building/testing the same tutorial. In the project selenium folder I had chromedriver_2.13.zip, but no chromedriver exec file. I tried unzipping it directly, but no joy.
So I installed protractor globally using sudo npm install -g protractor, which installs the files at usr/local/lib/node_modules/protractor/selenium/ (on a Mac). In that folder the chromedriver executable did exist, so I copy/pasted into the project selenium folder and now protractor runs as expected using the npm run protractor command from inside the project folder.