There is a app to download from Application Store for Symantec Identity Suite?
Identity Suite Virtual Appliance 14.x
Identity Suite does not have any mobile 'apps' if want to access the mobile view from the Portal just access the URL from the phone's browser as normal.
Portal should automatically switch to the mobile view, or the people could go to the mobile view directly
http(s)://host:port/sigma/mobile
References in documentation:
Identity Suite docops under Solution Capabilities
Portal Mobile docops