Labs #15 and #16 were solved using a previous version of Burp Suite Professional. The new version has several UI changes that include a different set of steps to access the Burp Collaborator functionality.

Therefore, when solving the labs, follow the following steps to access the new version of Burp Collaborator.

1. Open Burp Suite Professional

2. Click on the Collaborator tab.

   

3. Select the Get started button.