I found this link on the AKO page:
"I'm Navy - Where do I get the CAC middleware for home use?"
I have placed all of the places I know of at: https://militarycac.com/Navy.htm
Visit the Navy PKI site (CAC needed).
https://infosec.navy.mil/PKI/tools.html#softwareSeems kind of strange to me, that you have to have a CAC to be able to get to the CAC software.

I logged into the site, and here is what the above mentioned website states:
Activcard/ActivClient
ActivClient 6.1 is now available - Updated 7/10/07. If you have previously registered for the ActivClient 6.0 software you will not need to register again.
To request these licenses, a Designated Issuing Authority (recommend IAM) should send a digitally signed e-mail to
ActivClient6.1@infosec.navy.mil. The following information should be included in the e-mail:
Subject line: Request for ActivClient 6.1 for (COMMAND NAME) POC information for Issuing Authority (Name, E-mail and Phone Number):
Number of CAC Middleware license required for upgrade:
Number of CAC Middleware licenses required for command approved OWA:
POC information for Command IAM:
Please send any questions/comments to
itac@infosec.navy.mil.
This seems kind of a long process where a normal end user would not be able to do it.