I believe only creators / Collaborators of the Base / Interface have the access to share an interface with others?
On your interface, if you click the top right 'share' button while in Edit mode, you will get the option to share your interface with anyone by email / existing users.
It will give you the option of selecting which interfaces you want to share, and you can define what access they have too - Edit, Commenter, Read-Only 👍
This Share button also allows you to manage / amend the access people have to this interface by clicking it, and then selecting 'Manage Access' at the bottom.
I hope this helps!