Many times you are given a link from your studio to a file share site. When you open it, instead of seeing WAV files you can download and listen to, you see some weird files like DDPID, IMAGE.DAT, etc. This is what's called a DDP file set. You can see more information on what that is here:
https://support.discmakers.com/hc/en-us/articles/209221118-What-is-a-DDP-master-
What you will want to do after clicking on the link, is find the download/download all button.
This will download all the files into a compressed(zipped) folder, which is exactly what we need. You will usually be able to find this file in your Downloads folder on your computer.
Now you will want to log into your account, continue your project, and get started on your content. For DDP, you want to make sure you selected the DDP option.
Now you can simply click upload, find the file you downloaded on your computer, and proceed with your project.