Thank you for letting me know. This plugin has been off my radar since it hasn't received updates in a significant amount of time, but you're correct in observing that we appear to also have an outdated version on top of that.
From the comments on the Spigot resource page, it seems like the latest version may be intended for 1.15 and not 1.16, so there's still a chance that it won't work. If it's still not working, please let me know and I will just remove this plugin from the panel.
EDIT: I think I actually misread your post initially. If it's partially working, please check the logs -> latest.log file in the file manager after trying to use the plugin / right clicking. Then we can see if there are any errors there.