As a cloud-based system, Slick updates are pushed automatically via your internet browser. No need to download or install anything.
You should see a purple banner saying "Slick has updated, click here to see changes"
To update, click the button then hit refresh.
The latest version number will show at the top of the menu:
If your browser does not automatically show you the purple button, here are the steps to 'forcing' an update
Close all windows / tabs on the browser where you are logged into Slick
Open a new tab
Login to Slick & click refresh
Check your version has updated: