This is a know issue which is being investigated. You can follow the RSA Link Community migration status here: https://rsalink.statuspage.io/
Try raising the case through legacy portal instead, if you have registered for RSA Link prior to Feb 18th. https://rsaportal.force.com/customer/500/o
This error indicates your company is blocking the site box.com. You'll need to talk to someone who controls firewall rules to get an exception so you can upload and download from box.com.