You can always decide to turn on or off the approvals for your members, opportunities, or organisations / groups / projects. When you get a new registration or when a user creates a new opportunity, as an admin of your ecosystem, you can use your admin panel and approve or reject these.

When you get a new registration or when a user creates a new opportunity, you get an email notification to visit the dashboard and approve or reject these registrations.

You can simply go to your admin dashboard, review the relevant section (Members / Organisations / Groups / Projects / Opportunities), review the application, and decide if you want to approve or reject it.