Do you have a “normal” direct Internet connection? What I mean is, are you behind a proxy or using some kind of firewall? I ask because in your log I see this:
2017-11-11 18:52:39 [WARNING] extra.py(430) has_connection(): <urlopen error timed out>
2017-11-11 18:52:40 [WARNING] extra.py(430) has_connection(): HTTP Error 403: Forbidden
There’s also this error when trying to detect your hardware, but this shouldn’t be a problem:
2017-11-11 18:53:37 [ERROR] select_packages.py(291) select_packages(): Error in hardware module. An exception of type FileNotFoundError occured. Arguments: (2, 'No such file or directory')
And the fatal error:
2017-11-11 18:53:37 [ERROR] pac.py(567) cb_log(): could not open file /var/lib/pacman/sync/antergos.db: Unrecognized archive format
It looks like Cnchi (the installer) cannot update the repository database.