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See the below screenshots that enables to install unknown apps on Oreo for Chrome app (you need to enable on the app from where you want to install the apk):
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Go to Settings > Apps & notifications or go to Settings > search for unknown > Open the app (Chrome, Firefox or file manager app etc) > Install unknown apps and enable Allow from this source Or you can do it other way: Let’s say, you have downloaded the Fallout Shelter Mod APK file on Google chrome or firefox browser on your phone. Select the actual app through which you want to install the Fallout Shelter mod app. – For Android Oreo or later, clicking on Install unknown apps which will take you to a list of apps. – For Android Nougat or lower version click on Unknown sources and enable that setting. To do that go to Settings and search the word unknown
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Visit the Downloads section to get the downloadable APK file. Where to Download Fallout Shelter APK (Mod) file?
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