What you observes could be OS depended,. Vim has its own copy paste buffers (y,p etc) and the OS has its own. Traditionally highligh to copy and middle mouse button to paste on Unix. Windows has 2 methods, ctrl-c,v but those are also bindings in vim so only the older less known crtl-insert,shirt-insert works.
Copy paste is definitely built in, there is no need for extra plugins.