koobas.hobune.stream
How to create a sprite atlas?
I was also able to make [SpriteAtlas] up to unity 2019.4 version. However, in unity 2020.3 version, the menu to create [SpriteAtlas] disappeared. Is it a Unity bug? 
Sprite Atlas is now under "2D" section right under "C# script"
Thank you for answer. It seems that the 2D Sprite package was not imported and was not visible. Now my problem is solved.
