sentora install error

[laci]

Hy!
I want to install from scratch, i have Centos 6.8 instaled end i get som error..
-- Updating+upgrading system, it may take some time...
Loaded plugins: fastestmirror
Setting up Update Process
Loading mirror speeds from cached hostfile
Error: Cannot retrieve metalink for repository: epel. Please verify its path and try again
Loaded plugins: fastestmirror
Setting up Upgrade Process
Loading mirror speeds from cached hostfile
Error: Cannot retrieve metalink for repository: epel. Please verify its path and try again

-- Downloading and installing required tools...
Error: Cannot retrieve metalink for repository: epel. Please verify its path and try again
Error: Cannot retrieve metalink for repository: epel. Please verify its path and try again
Error: Cannot retrieve metalink for repository: epel. Please verify its path and try again
Error: Cannot retrieve metalink for repository: epel. Please verify its path and try again

-- Downloading Sentora, Please wait, this may take several minutes, the installer will continue after this is complete!
WARNING: cannot verify github.comâs certificate, issued by â/C=US/O=DigiCert Inc/OU=www.digicert.com/CN=DigiCert SHA2 Extended Validation Server CAâ
Issued certificate not yet valid.
WARNING: cannot verify codeload.github.comâs certificate, issued by â/C=US/O=DigiCert Inc/OU=www.digicert.com/CN=DigiCert SHA2 High Assurance Server CAâ
Issued certificate not yet valid.
2000-01-01 13:51:38 URL:https://codeload.github.com/sentora/sentora-core/zip/1.0.1 [21798411] -> "sentora_core.zip" [1]
./install: line 529: unzip: command not found
/bin/cp: cannot stat `/etc/sentora/sentora-core-1.0.1/.': No such file or directory

Thanks