Thank you for that suggestion, scook.
When I mouse the [Install] button under the “Apps” tab, a screen appears with the heading “Select the add-ons that you would like to install”. The four options are Studio Instruments Suite, Drum Replacer, Melodyne and Theme Editor. But it does not appear to matter how many I check. When I subsequently mouse the [Install] button, the message “Downloading… (0/2)” is displayed and the installer program just seems to idle.