Restrict the visiblity of your space to your organization members only.
Private spaces can only be read and edited by members of your organization (following your teams permissions).
Visiting your private space will require to be logged-in and have the read permissions to access it. This is the more secure way to keep your content private to a specific group of people.
If you need to share your private content to a larger circle than your organization, you can use shareable link.