Thank you for that serial number, the one that was giving you an error did have a duplicate record that was causing issues, I've freed that up for you so you should be able to add that serial number now.
If the APs won't connect to the HiveManager, this guide should help you troubleshoot CAPWAP issues: https://thehivecommunity.aerohive.com/s/article/CAPWAP-Guide-for-HiveManager-NG
To my knowledge support has always been a paid service, or at least in the last 4 years for certain. We are getting more diligent about checking for support when creating support cases. We are a fully channel based company, which means pricing information comes from your Aerohive partner, so they should have been keeping you updated on the price changes or deals that were available.
You can always get support for free here on the community, or if you don't want to post your question or information publicly you can email me directly.
