Help mounting external storage to my cloud

Hello , I have recently installed Nextcloud on FreeNAS and I have enabled external storage. I can access external storage when I allow “everyone” with full access to folder.
What is the proper way to mount external storage to Nextcloud ? What is the default user for Nextcloud ? Which I may add as owner to my dataset ?

You can mount external storage via admin user (or special dedicated user) and then share the folder to everybody. So the user does not change if a single user leaves the group. You have to create such a user yourself, there is no default user for this.