Using Repeating Group to Create Column of User Tasks

I’m trying to create a basic task-tracking application. A user fills out a form where they enter the task details, and they assign the task to an existing user via a dropdown menu.

The Question: how can I automatically create one column for each user, and have each task that was assigned to the user listed in individual rows within that column using repeatable groups?

I feel like this should be simple but I’m having a hard time combing the task object with the user object in a repeatable group.