Where are you getting this message?
Viewing post in Date Time❤️: Melissa❤️, Morris❤️, Anna❤️ - Demo out! - comments
Do you have certain security settings that may prevent you from running an app not specifically from an app store?
You may also want to try downloading it from Steam if you're having trouble with your app settings. - https://store.steampowered.com/app/2313010/Date_Time_Melissa_Morris_Anna/