You picked a plugin that is no longer in development and is not supported by the author. I would not start a new project with EasyTabs. The last updates was four years ago.
You can check the GitHub Issues to see if others have solutions to any problems. Or to commiserate with others stuck using a dead plugin.
Assuming it is THIS "Easy Tabs", and not some OTHER "Easy Tabs"
Always check the freshness date on your plugins! See if they are currently-maintained, if there are a lot of open Issues, etc.
You have SERIOUS HTML errors, including unclosed tags. You need to at least fix the serious errors first.
If you do not get any error messages, you're looking in the wrong place, or you need to use a better browser! (Chrome has the best inspection and debugging tools.)
Is this an update to an old project? You've used a LOT of obsolete HTML!