Trouble playing webm videos from Google Drive & Google classroom on iOS 13

Our kids' teachers have been posting webm files for students to watch via their Google Classroom. Some are direct links to the webm files on Google Drive. Others are embedded into Google Slides presentations. We have tried through the Google apps (classroom, drive, slides, etc.), safari, and chrome. All devices are running iOS 13.4.1. The webm videos do not play on the kids' devices: iPad 6th Generation (MR7J2LL/A). The webm videos will play on the parents' devices: iPad Pro 9.7-inch (MLN02LL/A), iPhone 11 Pro (MWCR2LL/A), and iPhone 11 Pro Max (MWHC2LL/A). I really want to get this working on the kids' devices. Their iPads we bought for Christmas 2018 so they are only 16 months old. Please help.