There are two USB-C ports on the MAC. For the first USB-C port (the one closest to the back of the computer), make sure that the Clickfree is straight and use some force to push it in all of the way so that it registers. This is how Apple designed their MACs to be and it is a tight fit.
For the second USB-C port, it may seem loose at first, but push it in all of the way until you hear a click.