You can either download files one at a time, or download the entire package at once.
Any project participant can download a submittal's files, not just recipients of the submittal. These are the rules:
Go to either the Documents or My response tab and click the link for the individual file you want to download. Clicking the file link automatically downloads a local copy of the file. If the file is a PDF, the PDF opens in a new window so that you can mark it up using the PDF Markup service.
or
Click Download content to download the entire package. A ZIP file containing all the documents in the package (including the cover letter) is downloaded to your computer or device. Extract the contents of the package using your preferred unzipping software.