More like this? Subscribe

Apps that do not originate from the official Google Play Store cannot be installed on the Oppo smartphone without access rights, so the app must be explicitly allowed (for example, the file manager) to install an .apk app from an unknown source.

Android 11 | ColorOS 11.0
Step 1: Tap on  Settings
Step 2: Tap on  Security
Step 3: Tap on  Unknown source installations
Step 4: Turn On/Off the desired  App
  1. Tap on Settings
  2. Tap on Security
  3. Tap on Unknown source installations
  4. Turn On/Off the desired App
Download instructions?
If you need the manual often or offline, you can download it here as a PDF document for free. Download

Oppo Instructions