In general, we stick to the EOL policy from Atlassian in regards to supporting Jira Server and Data Center versions. For detailed information, please check out our version history on the Atlassian Marketplace.
As an app built on top of Jira, we try to cover all platforms, that are supported by the host application. Please refer to the supported platforms documentation for your Jira version.
That's being said, we do not support Internet Explorer 11 and below beginning with JWT 3.0 as an exception to our general rule above.