This is a very interesting project/airdrop, even though it still is not clear to me how you will be able to share the future airdrops with community
Thanks for asking.
Castle holders will receive airdrops from other projects/coins who will be using the Castle Airdrops Platform, which will launch in some days.
It is a very easy way for projects to get more exposure, without all the work involved in processing airdrops manually.
Castle's Platform Automates the Airdrops.
The partner project doing the airdrop will have different options when it comes to the requirements to get the airdrop.
I hope this answer is helpful.
If you would like more detail, the white paper may help you understand better.