The spin-in will be hosted on Zoom. The room holds 100 people, and you can join and leave any time during the spin-in, which will start March 22 at 5 PM and will go until 8 PM.
If you're new to zoom, it's a videoconferencing platform that you can "dial into" from your computer or your phone. You can either preinstall the app or just follow the prompts when you join the meeting. Here's a quick tutorial.