Babbage installs as a plug-in to CA Harvest Workbench.
From the main Workbench menu, select
In the dialog that opens select the Search for new features to install radio-button, and click Next.
On the next page of the dialog, click on the New Archived Site... button and navigate to the folder where you have downloaded Babbage. Select the downloaded zip file and click Open. Click OK on the Edit Local Site dialog and the zip file should appear in the Sites to include in search list. Click the Finish button.
Tick the checkbox next to the Babbage plugin and click Next.
Select the I accept the terms in the license agreement radio-button and click Next.
Click Finish and then click Install when prompted to verify the feature. Say Yes when asked if you wish to restart Workbench.