Hi, The steps follow as below:
Download the Itch.io app (https://itch.io/app)
You should see a hub of all PURCHASED GAMES
Right-Click "That's Not My Neighbor"
Click on "check for update"
Download Update
Alternative Option:
Uninstall That's Not My Neighbor
Download the Itch.io app (https://itch.io/app)
You should see a hub of all PURCHASED GAMES
Redownload That's Not My Neighbor
Updates should be all automatically downloaded