From what I've seen on the official website, you can transfer the files to their storage area using the FTP protocol. You can use a client like FlashFXP or WinSCP. These applications support many other protocols among the FTP one.
Once you transferred the files, login on the main web interface and add the website files from their storage device.
Also, initiate Trellix on your PC and load the main file of your website (typically index.html), and the other resources will load as long as they're properly defined in the HTML file.