First off, welcome to PMC (kinda, since you did join in October 2018 and only posted now from what I know), but I digress. That's a pretty awesome build and I commented on the video, but for those who didn't see it, here's what I said:

Pretty clever way of using Blender as a base for the island; for sure I would have thought you just done a lot of commands using WorldEdit.I also like your technique on making the base for the castle, and the end results looks extremely eye-pleasing.All in all, this is a very good video and I'm surprised by its quality. I hope the commissioner is happy with this!

I'm definitely giving you a subscription for this here and on YT; can't wait to see more of your work.