How to install via Composer?

I'm using Drupal 8 with Composer and I'm trying to install the 8.x-1.2 version of this module. I have installed the Colorbox plugin in /libraries/colorbox as required in the installation instructions, but I cannot get this module to install at all. Each time I try to install it with Composer, I get the following error:

composer require drupal/colorbox
Using version ^1.2 for drupal/colorbox
./composer.json has been updated
Loading composer repositories with package information
Updating dependencies (including require-dev)
Your requirements could not be resolved to an installable set of packages.

  Problem 1
    - Installation request for drupal/colorbox ^1.2 -> satisfiable by drupal/colorbox[1.2.0].
    - drupal/colorbox 1.2.0 requires jackmoore/colorbox master -> no matching package found.

Potential causes:
 - A typo in the package name
 - The package is not available in a stable-enough version according to your minimum-stability setting
   see <https://getcomposer.org/doc/04-schema.md#minimum-stability> for more details.

Read <https://getcomposer.org/doc/articles/troubleshooting.md> for further common problems.

Installation failed, reverting ./composer.json to its original content.

It keeps complaining that it cannot find the plugin. I have tried installing the plugin from the Github link on the module page, and also from http://www.jacklmoore.com/colorbox/ and I keep getting the same error above.

What am I doing wrong? This is driving me nuts at this point. Thanks!