Google Hangouts/Meets is a Video Conferencing Tool with a chat function as well. Google is in the process of separating Hangouts to Google Chats and Google Meets, so currently has given schools access to their premium video conferencing service Meets until the merge happens.
Nothing needs to be downloaded onto the chromebooks Hangouts/Meet it is part of the G Suite tools and is available already.
To attend a meeting your child just needs to click the link they receive in their email or calendar to attend the Meeting.
By default when using a school account only a teacher can start a meeting.
If you are using an iPad you would need to download the Hangouts/Meet app from the Apple Store or Google Play Store