A new version of Topo vertex maps is in the works (2024).
see : https://c4d.freshdesk.com/en/support/solutions/articles/4000202166-topo-vertex-maps-2
For the the old version .....
Please read this general plugin install faq...
In general, on MAC, for R15 it is best to install any plugin to the user/plugins folder.
on a PC, or pre R15 MAC, you can install to user/plugins or APP/plugins , it does not really matter which.
Topo Maps contains 2 custom tags, and these can be found in the standard tag list.