You can’t run setup.exe from InstPkgs folder directly, these files are stored only for remote installation or for creating msi package.
In deployment task’s properties you can select option to create msi, then run it on client computer.

To check admin access, run this command on server:
net use * \usermachine\c$
If the c$ share isn’t mapped, check in client’s control panel - folder options, if you don’t use simple file sharing.

Also send me Remote installation log from ADNM console (under View menu).