Let's start by accessing the project's edit page, to do so find your project in the projects page and click the cog icon.
Then get to the files tab and click on the images linked to your source.
The process will take a few minutes, you will receive an email once it is done. At that point you can go back to your project's edit page, still in the files tab, scroll down until you find the available other files category. In there you will find your images, check that the status is validated and click download to get them on your computer.
In case of any problem or difficulty, please do not hesitate to contact the platform's team.