In your logs, I see:
MSI (s) (3C:50) [09:51:41:115]: Note: 1: 2205 2: 3: Error
MSI (s) (3C:50) [09:51:41:115]: Note: 1: 2228 2: 3: Error 4: SELECT `Message` FROM `Error` WHERE `Error` = 1721
Info 1721.There is a problem with this Windows Installer package. A program required for this install to complete could not be run. Contact your support personnel or package vendor. Action: removeExeInstaller, location: C:\tmp, command: C:\tmp\Uninstall Mattermost.exe /S
I’m not hearing any other reports like this. Maybe try downloading it again? I’d also suggest looking through all of that output for any errors, warnings, etc. There may be more info socked away in there that could help.
You can also try the Developers channel Mattermost