AMIGOPOD PowerConnect W Clearpass 100 Software Manual page 5

Click the Download File button and a file named amigopod Certificate
Authority.p7b will be downloaded (the precise name depends on the common name
for the CA certificate).
This file must be imported as a trusted root certification authority on any client
wishing to authenticate using this RADIUS Server. The reason for this is that the
server's identity must be established via a trusted root CA in order for authentication
to proceed. When using a well-known third party CA, this step does not need to be
performed as the necessary trust relationship already exists in most clients.
Importing a root CA in Windows Vista
See the following screenshots for guidance.
Open the .p7b file from Windows Explorer:
Select the certificate in the list. Right-click it and choose Open