This dialog helps you to add MySQL driver in order to connect to the MySQL database via plugin. It appears when the MySQL driver cannot be found in the following cases:

The following are details about options in the dialog:
Add
Browses to select the MySQL driver jar file on your local disk.
OK
Loads the selected driver into the MySQL connection plugin and opens the Connect to MySQL dialog.
Cancel
Cancels the action and exits the dialog.
Help
Displays the help document about this feature.