Added some pokes to your message.
With your install; have you tried installing offline with running installer as admin?
Also launch the taskmanager & kill any instances of pi server.
When offline (not connected) to internet disable the antivirus.
Then launch installer as admin.
Once install finished. Re enable antivirus & then you can safely reconnect to internet.
Run Piplay & see if it works.
Alternatively you can leave Antivirus on & Run as Admin.