Before you proceed, you need Spaces installed on your phone.
When you want to moderate the incoming membership request, to make sure the correct member is allowed to Space, you can choose to enable moderation and the Space connection request would be kept in pending state. The Owner/Admin would have to confirm the request & only after that the member can be a part of the Space.
How to moderate incoming member requests to join a Space?
Step 1 - Open the Space in which you want to moderate the members & click on the three-lined menu icon at the top right corner of the screen.
Step 2 - Choose the Settings button
Step 3 - Navigate below and enable Incoming membership request will be moderated.
You are done!