Accessibility missing from the Privacy tab
Your version of macOS predates this setting. You don’t have any restrictions to grant as they are not in place.

Can you validate your macOS version (or perhaps it’s still called OS X) from About this Mac and also cross reference the driver software version and requirement?

If in the end it’s not working, we might need a follow on question documenting the versions for someone to help. Since there are dozens of macos versions and many dozens of accessories that have tablet form, it’s not likely there’s a single solution for all cases you report of the hardware not working.

Nothing is likely wrong other than perhaps the wrong version of OS or wrong instructions being followed for the install.