Hi Laura
I'm not sure what French translations Toolset uses for terms such as Content Template or Layouts. You may find it easier while working on this part of your site to edit your profile and specify English as your language (just the language you see, not the site language) so that what you see on your site matches what you see in the documentation.
Let me briefly describe the relationship between Layouts and Views templates and then you ask me again once you have understood and you are still not seeing what you expect to see.
So, when you view content on the front-end, how it appears is normally determined by your theme, which uses different PHP templates to generate the output, depending on what is being displayed.
For posts, including custom types of posts, the theme will normally use a template single.php to generate the output.
Now, if you have added custom fields to your posts, which your theme doesn't know about, and you want to output them then the first option would be to edit the single.php file and add the PHP required to show such fields where you want them.
But you don't want to write PHP, which is where Toolset comes in.
The next option is to use Views.
Views lets you create Content Templates where you insert the fields, both standard fields and custom fields, taxonomy terms etc., where you want them.
When you assign such a template to a post type what happens is that when the theme renders the output for that post using single.php Views intervenes and swaps out what the theme would render and replaces it with what you have designed with your Content Template. (It is actually only replacing the part of the output that the theme renders using the_content() function.)
Layouts are an alternative way of doing the same thing, and you would do one or the other. Layouts is a page builder and so it gives you some more control over the placing of content within your template, e.g. in columns or a grid. It is nothing you can't achieve with a Views Content Template and the necessary CSS, but provides a more visual way of constructing the page. They are otherwise the same. If you try to assign both a Template Layout and a Content Template to the same post type, Layouts wins.
Now, when you add Divi to the mix, the first point to note is that we suggest you do not use Layouts. Divi has a page builder, Layouts is a page builder, and two page builders invites problems.
There is also an additional complication that Divi CSS conflicts with Bootstrap CSS (which Toolset uses, especially Layouts), and so we recommend you disable Bootstrap at Toolset > Settings.
That said, the expected use of Toolset and Divi is that you would create a Content Template using Views that you assign to the post type in question, and you may optionally design that template with Divi if you like working with the modules it offers. When you want to add custom fields to the template you would need to insert them into a Divi text module in this case.
In light of that, let me know if you still have any questions.