The directory sites/default/files does not exist. An automated attempt to create this directory failed, possibly due to a permissions problem. To proceed with the installation, either create the directory and modify its permissions manually, or ensure that the installer has the permissions to create it automatically. For more information, please see INSTALL.txt or the on-line handbook.
When dealing with SELinux we need to update context of the /var/www/html/sites/ to read and write:
chcon -R -t httpd_sys_content_rw_t /var/www/html/sites/