Name The Theme And Functionality

Hello, I am a freelance and one of my clients is fall in love with the functionality that “everydaycarry.com” owned, I have asked this question on many, many forums but all said they are using custom coding and no such plugin or theme exists. So, I am still searching for the theme name and the plugin for this functionality where new users or existing ones can submit their resources. link is here for the functionality: https://everydaycarry.com/submissions

For WordPress, you can try any of these plugins -
https://wordpress.org/plugins/tags/guest-posting/

Sure, i will try your suggestion and will update here If that worked or not, BTW what do you think about the theme?

I checked its source code. That’s not an WordPress site.