Solutions:
1. To install apps from an unknown source, please follow the path below:
realme UI 7.0 & 6.0 & 5.0: Settings > Security and privacy > More security and privacy > Installation sources > Turn on the corresponding application switch to install the app
realme UI 4.0 & 3.0: Settings > Password & Security > System security > Installation sources > Turn on the corresponding application switch to install the app
realme UI 2.0 & 1.0: Settings > Security > Unknown source installations > Turn on the corresponding application switch to install the app
realme UI R & Go & S & T & U Edition: Settings > Apps & notifications/Apps > Special app access > Install unknown apps > Turn on the corresponding application switch to install the app
2. Poor network connection. It is recommended to download using WiFi or a mobile network.
3. Insufficient storage space on the phone. Please uninstall apps or delete files and data cache to free up space.
If the above methods do not solve your problem, please back up your data and visit the nearest authorized realme service center for testing.