Help Request: Plug-in Fomidable Slack

Installed the plug-in today. After activation, the plug-in displays this notice “Warning: This plugin has not been tested with your current version of WordPress.”

Formidable Slack doesn’t show up in the left menu to add the Slack API. Guidance or resolution?

https://ww.wp.xz.cn/plugins/formidable-to-slack/