IDE to USB device not being found

First make sure the IDE drive is already connected to the adapter and the drive has power. Then connect the USB adapter to the computer.

What is the exact make & model of the USB to IDE Adapter you are using (provide a link if possible)?

Connect the USB IDE Adapter directly to the computer. Disconnect all other external devices in case one of them is causing a problem (except of course Display & Keyboard & Mouse).

Try restarting the computer & trying again. Perhaps even try while booted into Safe Mode.

What is the history of this IDE drive? Perhaps this old IDE drive has failed. Many times old hard drives which has sat unused for years may not always spin up. You can try connecting & disconnecting the power supply to the hard drive assuming the drive/adapter has its own power supply (do not do this with the USB IDE Adapter connected to the computer).

Do you have any other computer you can use to see if the physical IDE drive shows up in the OS (can be any OS for macOS, Windows, Linux). Does the USB IDE ADapter show up in the OS? For macOS, you need to check the Apple System Profiler's USB section....the adapter may only have the name of the USB chip used in the adapter & not the adapter name itself. The Apple System Profiler can be accessed by Option-clicking the Apple menu & selecting the first item. Other operating systems may not recognize the file system on the IDE drive (that is Ok) since we just want to make sure the adapter is seen and the physical IDE drive is communicating with the OS in some manner.