entering a table of content

ok so I am having problems with the Oda theme entering a table of content from the Single Template.

He does not show it.

I do not manage to have the table of content even with the Luckywp Table of content for SEO plugin installed.

I asked WordPress support and they said:

After some tests, we’ve found that adding a?Table?of?Contents?block to the Single Template will not work. What you can do is add it the posts themselves. To speed the process up, you can create a?reusable block.
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Also, we’ve noticed the theme currently installed on your site is Ona, a third-party theme. Since third-party themes is provided directly by the developer, you will want to consult the theme developer in case you have any questions about the theme (we can help you with the Site Editor itself, but?for?any specifics?of?the theme please refer to the theme developer).
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The same is true?for?the?LuckyWP?Table?of?Contents?plugin, which is a third-party tool as well.?For?any questions about that plugin, please refer to the plugin documentation or contact the developer.

I do not know how to contact the developers.

I am on their site https://deothemes.ticksy.com/submit/ but can not find the theme Oda on the themes options.

I have been told by the WordPress agent that they have a support page for the theme https://ona.deothemes.com/contact/.

I have tried calling +1-888-1554-456-123 but is a wrong number.

I will send them an email also to [email protected].

The page I need help with: [log in to see the link]