Somewhere in your itch account (My Purchases I think), or your email, you should have a code that you redeem directly through Steam. You don't have to link anything.
What about the other way around? Bought it on steam, and can't seem to find a steam key button for the APK anywhere, don't recall there being a apk when purchased, Engaging destiny and Endless Bounty both would be wonderful to play on mobile, cus I used steam link and finished it but it wasn't enthralling 10000%
