What part is not working ?
The entire addon or just the overlapping nameplates, because there is a Blizzard UI option, plus one in the addon ifself which do the same, with the addon usually overiding the blizzard version.
Try toggling the nameplates on if they arent already, by Shift+V or Ctrl+V - if the default blizzard ones are appearing, then the addon is likely not installed properly.
Try /tidyplates to check that.
Bottom right corner? That's not nameplates, that's the tooltip.
If your nameplates aren't showing up, make sure the box in TidyPlates to "Hide when out of combat" or whatever it's called is checked. You can check to see if it's working when OOC by hitting "V" (to show hostile/neutral plates) or Shift-V (to show friendly plates). Hit the same bind again to hide those plates.
Facepalm for myself there,
Why did I not think of the tooltip when they said that.
If you want to simply relocate that tooltip, then try Tipsy.
If you are looking for a full blown tooltip replacement with options, then TipTac, CowTip, etc are options.