This plugin sources your training schedule from https://openmat.training and displays the current week in a widget.
Go to the Openmat Developer page and generate an API key and shared secret.
In WordPress, go to Settings > Openmat API and paste in your key information and save.
Go to Appearance > Widgets and drag the Openmat Calendar widget into a sidebar, enter an optional title and save.
Styling of the widget is controlled through a single stylesheet (openmat.css), contained under the wp-content/plugins/openmat/css/ directory.