The "Fail to open the file. Please check if the file can be accessed." may be caused by a firewall setting which removes the CORS (cross domain) permission in http header. 

Because your files are uploaded from your Podbean admin site (http://admin.podbean.com/... ) to Amazon S3 directly, the CORS needs to be set as " Access-Control-Allow-Origin: *" to allow cross domain uploading. 

You should change your firewall to allow "Access-Control-Allow-Origin: *" in http header. This should resolve this issue. If you have any issues, please contact us at support.podbean.com.