Invite "works best for people with Office 365 business and school subscriptions, but also works great with any email -- Outlook.com, Gmail and Yahoo Mail included," according to Microsoft. With Invite, scheduled meetings will show up in the calendar of the account users sign in with.
Invite is somewhat different from the "Send Availability " feature that's in Outlook on iOS and Android, as it provides additional automation to the scheduling process, Microsoft's blog post says.
Microsoft's Garage is the company's tech incubator for lightweight consumer-focused apps for iOS, Android and Windows devices. The Garage apps are cross-platform, available in the Apple App Store, Google Play and/or Windows Store, where applicable. The Garage apps are all in the "experimental" phase, and are updated and improved based on user experience and feedback.