Currently the YubiKey Series 5 hardware token cannot interact directly with most applications on the Macintosh, so you need to use the Yubico Authenticator App to generate a code that you can then enter into your applications. At the moment it can only interact directly with Microsoft Edge or Google Chrome. However you may need to use the key on a Windows based computer and eventually you will be able to use it directly on a Mac, so it is a good idea to add the key to your account as a hardware token.
Step One: To do this you must first download and install Chrome or Edge.
Download Edge here: https://www.microsoft.com/en-us/edge
Download Chrome here: https://www.google.com/chrome/
Now launch whichever browser you installed and go here:
https://aka.ms/mysecurityinfo
Step Two: Sign in with your CWU credentials and then (if it doesn’t take you there directly) click on Security Info on the left hand side:

Step Three: Choose Add method:

Step Four: Choose Security Key and click Add:

Step Five: Then USB device, and click Next:


Step Six: At this point you will plug your Yubikey into your computer and touch the gold button. It will the ask you to create a pin:

Step Seven: Create a 4 digit pin for your key and hit Next. It will prompt you to touch the button on the key again:

Step Eight: After you touch the button click Allow on the next window (if it asks you to):

Step Nine: Now type a name for your key:

And click Next. Now the key will be added to your account and will work on a Windows computer and eventually a Macintosh. You can quit the web browser.