Does not matter if you are using child theme or only the Evolve Plus Theme.
As long as you have no modifications done to your Evolve Plus Theme, you can update using FTP.
My suggestion is to delete Evolve Plus Theme before uploading Latest Evolve Plus Theme. This is because, sometimes ftp overwriting fails without proper warning, or you missed the log message and you can end up having updated only half the theme.. or have empty files.. etc, causing PHP fatal errors.
At the moment, there are some bugs within Evolve Plus v2.0.0, I suggest you wait for next version.