We have a AIP-SSM 20, I installed a trial license while we wait for the contract. But I am not sure how I can get the signature files, since I cannot download it from the site and auto-update fails with authorization.
Is is possible to get these with a trial license?
The Trial License itself only affects whether or not the sensor will allow installation of the files.
The Trial License has no affect on whether or not your userid on cisco.com will be able to access the files.
Do you have a Cisco Representative that you work with? If so then contact him/her. They should be able to either get permission for your userid, or download the files themselves and provide them to you.
If they download them for you, you won't be able to test the "auto-update" feature, but will at least be able to manually install them.