Download Atoms Unreal from here.
Extract the Atoms Unreal folder from the zip archive.
Copy the Atoms Unreal folder to:
C:/Program Files/Epic Games/UE_4.22/Engine/Plugins
Licensing:
Importing and playing atoms caches doesn't require a license. For realtime live simulation you need to install an atomsRealtime license.
Floating license:
Set the env variable toolchefs_LICENSE = 5053@localhost (change localhost to your hostname where the license server is running)
Node lock license:
Set the env variable TOOLCHEFS_LICENSE_PATH to C:/Program Files/Toolchefs/rlm/atomsRealtime.lic or where your license is located