Do other templates work and only this one is the problem?
If you don't have any working template examples, it could be that your theme does not output the post content using the standard WordPress function the_content().
The easiest way to know would be to switch theme to twentytwenty and see if the template then works.
If so then it is a theme compatibility issue.
We may need site access to check the problem, so let me set up a private reply.
You may want to create a temporary admin user for me to use that you can later delete. And be sure to have a current backup of your site.
Hello, there appears to be a non-English CAPTCHA on the login screen, and I'm unable to complete the login process. Is it possible to disable this captcha temporarily, or provide a one-click login?
If you want to use the Block Editor to create Content Templates, we recommend you deactivate Toolset Layouts plugin. I have deactivated Toolset Layouts plugin and I can now see the Content Template applied correctly. I added the word "test", which now appears in the post content. Please check now.
We recommend you choose either Content Templates or Layouts, but not both. Using both Layouts and Content Templates will cause problems, because Content Templates override Layouts.
I have checked it in your website, it seems you have already switch to content template: hidden link
And Toolset Layouts is based on bootstrap framework, but Toolset Blocks plugin is based on WordPress Blocks editor, so you will need to setup the content template manually.
For example, edit above content template: hidden link
Click button "Block Editor", and design it as what you want.