The Atari VCS comes with two 4GB SODIMM RAM modules for a total of 8GB of RAM. The RAM can be upgraded to a maximum of 32GB.

• RAM compatibility -- The Atari VCS is compatible with DDR4-2400 SODIMM RAM. You must add RAM in pairs, so to achieve the maximum capacity of 32GB you would add two 16GB modules. Please note, SODIMM RAM is a different format that RAM used in desktop computers. Desktop memory will not fit in the Atari VCS.
  

        SODIMM RAM

Time and effort -- Installing RAM in your Atari VCS requires care to ensure you do not damage your VCS during the installation process. Installing the RAM itself is easy, but accessing it is much more difficult as the RAM is located on the bottom of the motherboard. To reach it you will need to remove the heat shield and unscrew the motherboard from the chassis. 

RAM Installation Guide https://atarivcs.com/content/RAM-Installation-Guide.pdf