[Plugin: AddThis] Addthis not showing in screen options

Hello,
i have isntalled the plugin and activated it. also i have created an account on the addthis page.
i understand that it should show on as a checkbox in the screen options, but i don’t see ti anywhere.
could it be a conflict with another plugin?
any help will be greatly appreciated.
thanks

https://www.ads-software.com/extend/plugins/addthis/