If you faced the error “Theme is missing the style.css stylesheet error” this means that you are uploading the main file downloaded from your themeforest account (which contains all files: theme, plugins, documentation,…), please make sure to extract the .zip file on your computer and then upload the file essentials.zip inside Theme folder.
For more information please check this article from envato website:
https://help.market.envato.com/hc/en-us/articles/202821510
