Hey,
The "Exclusive Content" feature was more designed for things that you *need* human interaction to fulfill, like sending physical goodies to your buyers, drawing something they ask you to, personalized things like that.
I don't think we have a way of automatically e-mailing something when a reward is bought (although that sounds like a nice feature request, I opened an issue here to track our progress on this).
Another option for your use-case would've been a file with a "minimum price" (you'd have to upload another file in the Edit game page, and check "Set a different price for this file").
Unrelated, but I really encourage you to:
- Use https://itch.io/docs/butler for uploading builds
- Tell your players to use https://itch.io/app to play your game
It'll let you only upload what's changed, and have your players always be up-to-date (the app download small patches automatically instead of re-downloading the whole thing!). You don't even need to zip it up first, it takes care of everything.