To get an evaluation license, see the PDF documentation section "Licensing AuthLite". You will need to install AuthLite on your domain first. After restarting the first DC and logging on, the AuthLite Configuration application will appear, with the required License ID.
If you need to buy YubiKey tokens for testing, please contact us. You can return them in good condition for a refund (less shipping) if you decide not to keep AuthLite.
You can also get YubiKeys from many other vendors including Yubico, the manufacturer. Make sure not to get the blue "security key" model, since that is not actually a Yubikey and doesn't support the OTP and C/R modes needed by AuthLite.
You may also find the "version 2" videos to be of interest, on the videos page.
AuthLite can be very lightweight when configured properly for your environment, but it has many complex possibilities that can be confusing when you are getting started. Please do not hesitate to open a support request from our support page if you get stuck or have questions about how best to configure AuthLite!