I got this error when try to upload the zip file downloaded: Could not find a handler capable of installing the add-on at Bugzilla-Default.zip. Check that the file is a valid add-on.
If I try to install directly from Marketplace, I got this error:
"Default Bugzilla Workflow" cannot be installed by the UPM. Visit the Atlassian Marketplace website to find more information about this add-on:
I am the latest trail verion 6.0.6 on Windows 7.