When installing Little Green Button, the installer will attempt to put in place the necessary Firewall Rules.
If this fails for any reason, a warning is displayed

Adding the extra parameter SKIPFIREWALLRULES=1 to the command line e.g.
msiexec /i lgbsetup-3.17.9067.msi /qn SKIPFIREWALLRULES=1
will direct the installer to avoid any attempts to modify the Firewall itself. Therefore the warning won't occur.
Please be reminded that for proper functioning of Little Green Button, it is imperative that the Network requirements are still met by other means.
Further .msi launch parameters can be found in Deployment To Multiple Workstations.