I am new to plugin development for Wordpress but not new to software development.
This question is to get an idea of the "best practice" style for the following question.
I need to make a form only available to registered users, who ideally have a username that is a specific numbers-only is that they already would have. Ideally, the user would register with this id as their username, their email, name etc. After logging in, they would have access to a form that would be created by a plugin. When they submit the form, it would add data to a custom table created by the plugin. I've seen a lot of resources for managing tables in Wordpress, so that's not an issue.
Is there a members plugin that has an API that would allow me to track their id (username) when they submit the form? Should I use the default user capability? What would be the best practice for this situation?