Realme
Allow Installations from Unknown Sources auf Realme
Realme UI blocks the installation of apps that do not come from the Google Play Store. This security layer prevents .apk files downloaded from browsers, file managers, or messaging apps from running without your explicit permission.
The setting that controls this behavior sits inside the security section of your phone, and it works per app rather than as one global switch. Each app that tries to install something outside the Play Store needs its own approval before the installation continues.
To allow it, go to Settings ➔ Security ➔ Unknown source installations. Find the app you used to open the .apk file, tap it, then use Turn On/Off an App to switch it on and confirm with Allow.
Once enabled, that specific app can request future installations from unknown sources without triggering the block again. Other apps still need the same approval individually.
Only enable this for apps and file sources you trust. Leaving unknown source installations active for apps you rarely use increases the risk of installing modified or harmful .apk files later.