Hi Stilldsust, were you able to find the Steam key?
We had some users reaching out to us about not finding the Steam key and we contacted itch.io support.
This is their response:
There are several issues which can cause this, including making the purchase under an email address that does not match their Steam email address. Those users should contact us individually to determine the cause in their cases. We are not showing any issues on your side, keys are available and are being claimed by players.