Hi Tolu,
Which Ubuntu version are you using?
I had to go on the official Nvidia website to make sure that the A4000 is compatible with drivers prior to 470. It looks like it is:
You might have to find a way to manually download the package of 460 and install it if setting the correct remote repository does not work.
I know it doesn’t help you, but I’m using Ubuntu 18.04 and most of the development has been done and tested in 18.04 with a laptop RTX 2070.