It looks like the Plugin’s tabby.js jquery script is being included as expected, but the code does not appear to be processed.
I would normally expect to see your site to be enqueuing the version of jquery included with WordPress, and no other version from:
https://www.ecotravelmexico.com/wp-includes/js/jquery/jquery.js
However a non-standard and out of date copy of jquery is being included from a non-https external URL.
You can see this in your page source:
http://ajax.googleapis.com/ajax/libs/jquery/1.11.1/jquery.min.js"
This might be the cause of the issue and may be due to another plugin doing something daft.
To troubleshoot this issue, temporarily deactivate all other plugins. Then if the tabs work as expected at that point, activate the other plugins one-by-one until the issue occurs again to identify whether a specific plugin was causing the issue. If the indication is that it does not appear to be a plugin causing this, try temporarily switching to a default theme such as twenty-sixteen to establish whether something in the theme migth be causing the issue.
