I’ve added the WP File Manager plugin so you can access file system from within WordPress. Because its a Ubuntu server, even with SFTP access the files are “owned” by the Apache user “www-data” and you can’t easily access them
Your downloads page will work now, There was a modification done with the plugin code in file class.Package.php ► line 260 preg_match('/[a-zA-Z_\x7f-\xff][a-zA-Z0-9_\x7f-\xff]*/',$key)