My understanding is that the Splunk for Cisco Firewalls app is intended to be an add on to the Splunk for Cisco Security Suite. According to the README.txt:
The Splunk for Cisco Firewalls add-on
allows you to consume, analyze, and
report on Cisco firewall data for
Cisco ASA, PIX and FWSM firewalls.
This add-on is designed to work with
the Splunk Cisco Security Suite;
install these together to access
reports and dashboards that give you
visual insight into your Cisco
So you'd want to install the Splunk for Cisco Security Suite app which provides the main screens for Cisco stuff. When the Firewalls app is added, it shows the additional dashboards on the Splunk for Cisco Security Suite app.
The same is true for the other Cisco apps. They mostly are addons to Splunk for Cisco Security Suite.