Where is the source of Xiaomi k30 suit unknown?

If the prompt of unknown source appears when installing the software in Xiaomi mobile phone or tablet computer, and the installation is prohibited, you can: Settings-More Settings-System Security-Unknown Source/Install Unknown Application, and open or select the corresponding authorized program to open it.

PS: When the device opens "unknown source" for the first time, it needs to meet the requirements of inserting SIM card and networking; The same SIM card is allowed to open three new devices every 30 days. If you upgrade to the latest MIUI system of Android 8 or higher, you don't need to turn on this function manually. When an unknown application installs software, you will take the initiative to request permission and allow the corresponding permission.