Stated supported browser versions are not supported.
Several places Teams' documentation/guidance states: "Use supported internet browsers, which include: Internet Explorer 11+, Microsoft Edge 12+, Chrome 51.0+, and Firefox 47.0+."
However, I've found that the most recent Chrome version which is supported is 59, and the most recent Firefox version which is supported is 52.
Otherwise the message to download an updated browser or use the Teams app is displayed.
This is on Windows 10.
Same on Chromium (Brave, Vivaldi) on Linux.
Can't get it to work.
Same on phones, edge and chrome say version not supported