To check if you have the needed access rights to the target PCs, please check the following:
On the admin computer:
- Try to access \\remotecomputername\c$ in Windows Explorer
- Try to access the remote PC's services manager: Services - Action - Connect to another computer...
Note: Remote installation will only be possible if you have access to the remote c$ share as well as the Services Manager.
On the client computer:
- Check if the Windows Firewall is disabled (the PC will be invisible in the network if it is enabled)
- Check if the admin account has a password