When you create a new Space it is visible to only you by default, no one will have access to the Captures that you store inside of it and they will not show up in search results.
However you'll get the most out of your Captures by making them visible to other participants and team members. So it's great to have shared Spaces where everyone can participate and add their own Captures, images and artifacts. You can add team members to a Space by going to the top right-hand corner and clicking on the 3 dot menu button.
Once a participant has been added they will be able to listen to past Captures, search them for key information, and add their own Captures. All participants will also be able to add or remove participants as well as labels.