The most common error is user-side. The iPhone must be unlocked, and the "Trust This Computer?" prompt must be accepted. Without this handshake, the driver will not mount the device storage.
There are three ways to install the necessary drivers on Windows.
When you install the Apple Mobile Device Support package, you are also installing the system.
How to Install iPhone Drivers in Windows 10 (3 Different Ways)
If the device appears under “Other devices” with a yellow exclamation mark, the driver is not properly installed.