According to the contact page for itch.io when you check how to get support relating to Among Us, the support email is:
us@innersloth.com
According to recent communication from Innersloth where they've been telling people how to contact them, the support email is:
support@innersloth.com
I emailed the first address a week ago and have gotten no reply. I emailed the second address 4 days ago and have gotten no reply. Once the second email gets past a week with no reply, I'll be contacting itch.io to request a refund from them.