Yes, that email is fine, or simply use this form.
The developers are working nonstop in order to make this game, and they can't be inundated with numerous private messages on Discord. However, getting in touch with a moderator on the Discord will ensure that you get the help you require. I recommend that you have all the necessary information easily accessible before contacting us; so have your Paypal receipt, the email assigned to your Paypal, and specify the time when you backed.
We'll get you sorted!