I think the itch.io client does auto updates as well?
In any case, if you send me your email address I can send you a Steam key. They take a day or two to generate/be approved, so there will be a little delay.
I tried to find your email address online but couldn't find it and it is understandable you don't want to be spammed or anything.
Minding sending it to rwbypi38@gmail.com with the title "steam key"
Done.