I need user ID to be same as Username

I need a way to have my external plugin to read each of my users as their username. At the moment it seems like it is only reading them as their user ID.

I would like to have the user id to be the same as the username. I found this resource but I'm not sure if it is what I am looking for (based on the info above) or even how to implement it.

Please let me know if you have any ideas how to make user id same as username.