Step 1: Download the extension

Step 2: Unzip the files

Step 3: Upload it to your Magento root directory

Step 4: Enter the following at the command line:

    php bin/magento setup:upgrade

Step 5: Clear Cache in the command line using

    php bin/magento cache:flush

Step 6: Redeploy your theme using

    php bin/magento setup:static-content:deploy 

if your site uses multiple languages you will need to specify them on the previous command like so 

    php bin/magento setup:static-content:deploy en_US en_GB