Please go to skype.com and click "Downloads".
You will be redirected to another page where you can select the needed Skype version. You can choose Skype for Windows or Skype for Mac by clicking on the arrow, then selecting the desired Skype version.
IMPORTANT: For the Windows version of the app, you need to click on "Get classic Skype" as it is shown in the image below.
Please note that the plugin only works with the classic version of Skype!
You will be asked if you allow Skype to make changes to the Device and you will need to click "Yes" and continue the install process by selecting the options you want and clicking "Continue".
After the installation process has been completed, enter your credentials and you are good to go!