If it's a brand new site your setting up from scratch. It might be worth removing all files and upload again. Sometimes odd things happen when uploading files and if your site is a new install I would trying doing it all again from fresh. See if you have the same issue?
In fact, if you use cPanel I would upload the ZIP and extract it on the server using File Manager in cPanel. Rather than FTP files to server individually. Your much more prone to having a bad file upload using FTP, uploading all files individually because there are like nearly 3000 files in XenForo that can cock up.