FileBird has a unique setting option which allows each WordPress Admin user to have access to folders created by each one of them alone. So, for instance, if a user with the name "Bruce" is logged in to the website's backend and then creates folders in the gallery, he alone has access to those folders, similarly, the same condition applies for other users as long as they have access to the website's backend.
However, this setting is only set to work with all the normal WordPress Admin users, so any customized user admin functions using third party plugins may not work.
You only need to turn ON this option under WordPress Settings => FileBird. See gif image reference below: