This oscilloscope does not have support for IVI driver, that is why you can't connect to it. Only the newer 4ch models (DSO4xx4BC) can support SCPI commands via USB using the Keysight IO Libraries.
For the 2CH models, your only option of communication with the device is to use a very basic (to say the least) proprietary software that you can download from the product's page.
You installed the wrong software. The oscilloscopes DSO4004C (4 channels) and DSO4000C (2 channels) series are completely different, with different hardware, firmware, USB drivers and PC software.
You are trying to use the driver and software of the DSO4004C with a DSO4000C oscilloscope, it will not work. Download and install the correct files that it will work, it is a very basic program, with no practical use, but it works.
Post time 2020-5-30 05:26:05