I've associated your user record with your account and enabled download access in Hive Community for you, per your support. To open cases via Hive Community you'd need to purchase Global Select support. To open a case with the VAD support, you'd need to contact your partner. If they are not helpful, not responsive, or not offering to make a case with ATAC for you for issues they are not sure how to solve, please let me know who you are dealing with directly at communityhelp@aerohive.com, and I will make sure you get the help you need.
For the devices that did not connect to HiveManager, this guide can help you get them reconnected- https://thehivecommunity.aerohive.com/s/article/CAPWAP-Guide-for-HiveManager-NG
With HiveManager IDM is not a separate service like it was with Classic. IDM services that once required the external system are now included directly in to the HiveManager. This is one of many reasons why we can't import configuration directly from Classic to HiveManager.
For the first SSID with 500 users, if we can change the passwords to not use the characters that conflict with HiveManager, then we should be able to get the export function working for you so you can import them directly in to HiveManager. I'm guessing this is a PPSK SSID?
For the second SSID, could you tell me what security level it is, and what services you were using with IDM? There is no way to import a CWP object in to HiveManager, but if you can let me know what type of CPW it is, I can give you more information on how to rebuild that in HiveManager.