You can create a slideshow after your game by downloading the submissions from the Game Manager, then using a slideshow program of your choice on your computer.
To download the submissions, head to the "Submissions" tab on the website and click the "Download Submissions" button in the top right corner.
From there, select how you want to zip the submissions together (e.g. sorted by team or by mission), wait for the zip file to be created, and then download that zip file. Then you can unzip the zip file from your computer and create a slideshow however you’d like!
You can also download submissions individually from the Activity Feed or Submissions tab by clicking on the three dots next to the submitting team's name and selecting Save Photo/Video.
More information on reviewing and downloading your submissions can be found here.