Users are allowed to upload files as meeting creators and attendees. These files are saved to the uploads directory. You must already have this directory existing in the root of this application.
If files are not saving to uploads, one of these reasons may be the cause.
In constants.inc.php, we specify UPLOAD_SIZE_LIMIT in bytes. However, this value cannot be larger than the limits set on your server. Your limits can be found in your server's php.ini under post_max_size and upload_max_filesize.
If files uploads are not saving, it may be that your current user doesn't have permission to write to the uploads directory. Depending on your server settings, your server may upload files as the owner of the directory (the user used to install the application), or as the apache user. To work around this, you either need to change the owner of the uploads directory to the apache user or change Apache to run as the current user. Both changes require sudo access.
If you do not have sudo access, a non-optimal workaround is to change the permissions of uploads to 0777. However, this is a security risk.