Surely you can just set the permissions for the Anonymous user to post without the need for an extension - although you should be aware that you run the risk of being inundated with spam, with or without any extension.
Remember: You only know what you know and - you don't know what you don't know!
My CDB Contributions | How to install an extension
I will not be accepting translations for any of my extensions in Github - please post any translations in the appropriate topic.
No support requests via PM or email as they will be ignored