custom css not loading

I am trying to add some custom css following the instructions in the themer’s guide.

I created tribe-events.css in the tribe-events/ directory of my child theme, however it is not being loaded.

The plugin is installed on a single site of a multisite network. I am using a custom template which is also in the tribe-events directory, and it is working with no problems.

Any advice?

https://wordpress.org/plugins/the-events-calendar/