To download Client Tools like Policy Studio and Configuration Studio for the desired API Gateway version, the following steps needs to be followed. Please refer to the screenshots for clarity.
Navigate to https://support.axway.com/ and login
Click on 'Downloads'
Under 'Products' in the left pane, select 'API Gateway' and the appropriate version. e.g. 7.7
Scroll down and in the left pane, select the 'OS Category' as 'Windows' and 'Type' as 'Install'
Various Client Tools Install results will be shown for the selected API Gateway version
Click on the desired link and download the install file, using which Policy Studio and Configuration Studio can be installed.