WiX paid plan with connected domain is required to use Smartlook.
Step 1 Insert code
Your code is in Smartlook > Account > Sites > Tracking code.
Step 2 Log into wix. Go to Site Manager

Step 3 Go to tracking & Analytics > Custom

Step 4 Insert the Smartlook tracking code

Step 5 Enable the Smartlook Tracking code

Step 6 Publish your website

Step 7: Refresh your website
Now go to your site homepage and refresh browser.
To see visitors on your website log in to Smartlook.