It's easy as 1, 2, 3:

 One

Ensure the Cataloger screen reflects what to look for.

 

 Click image to enlarge.

Cataloger screen

 

 Two 

 

Click the [Catalog] button on the Cataloger screen...

let DLRoundup search & catalog.

Three

See your results on the Master Library screen that you can sort, search, update, launch and more.

Click image to enlarge.

Master Library screen