Black screen after startx and monitor reads HDMI out of range 75.0 kHz / 60 Hz

It is all right that way if copy&paste is not possible.

Your GPU needs the 340xx driver of nvidia which is EOL (end of life) and forget about gaming on such a gpu even good old AOE2 will not work properly on linux due zero vulkan support.

However, it is possible to install the 340xx driver manually if you need it:

However, I dont know if it works on the latest kernel version. Keep sure you run kernel 5.4 for that driver.