itch.io

Press escape and you should see the save button

if you scroll down, indivi said:
"Windows: C:\users\(username)\AppData\Local\UserData\Default\Lust Doll Plus

Mac: \Users\(username)\Library\Application Support\Default\Lust Doll Plus

Linux: \Users\(username)\.config\KADOKAWA\RPGMV\Default\Lust Doll Plus (May need to sudo nautilus if you don't have access to .config)

Android: \data\data\indivi.indivigames.lustdollplus (Requires root access)

If you're on android, don't uninstall before installing the new version. Otherwise, your save file should transfer automatically!"