Click "Parameters for PSHM" menu item which is a child of "Probabilistic Seismic Hazard Maps" on Download page and the following view appears.

You can select an archive format from "zip" and "tar.gz" using the radio buttons.
You can select a file format from "CSV file" and "Shape file" using the radio buttons.
You can select a reference date from the "Version" combobox.
Click
to download the PSHM parameters which are based on the settings mentioned above.