Hi
If you just download it, then game should be in Downloads
File name - SarahsHouse_v0.8.6.zip
If you alredy started playing and trying to find saved files then it should be in folder - SarahsHouse_Data
I too am searching for the save files. I originally downloaded the game manually and then moved to the ITCH app.
I located the saves for the manually downloaded version here: C:\Users\[YOUR USERNAME HERE]\AppData\LocalLow\AceStudio\SarahsHouse
I am yet to find where the ITCH app version of the game is storing it's saves which is proving painful!