Problems with Gutemberg and TagDivComposer

Hi, I have followed this article of slides galleries.

I have some problems to achieve the slide effect for this:

1.-When I try to edit a post I can´t see the TagDiv Composer option: https://prnt.sc/ou604y. Only I can see in the page editor: https://prnt.sc/ou60vc ¿Posts doesn´t have the tagdivcomposer?

2.-When I try to edit the text in the post I can´t see the classic editor but the Gutemberg editor: https://prnt.sc/ou61sc, I show this because with this editor I can´t find the option/button to include the media.

3.- If I use directly the upload gallery option in the editor and I use different images, like the cited article, when I push the next button, I can´t see the gallery settings like your article.

Thanks, I am waiting for your help.

I have seen that if I edit a post from my own template (editing a created post) it´s possible to find the WP editor like this image. I don´t understand why in the new post option doesn´t appear this and if I use some edited post I can see. It seems like two editors totally different.

Can anybody help me??

Ok, thanks for your reply.

I have only the main plugin installed, gived by the theme. I would want to resolve my doubts:
1.- Why in the post editor I can´t see the TagDiv Composer and in the Page editor appears?
2.-If I use directly the upload gallery option in the editor and I use different images, like the cited article, when I push the next button, I can´t see the gallery settings like your article.

Thanks for your help!

Thanks!

I have installed the theme in local with Xampp, so I think it could be difficult. I will try to installed from 0 the theme, but as you show in the article, I should see the gallery settings in the post editor, isn´t it? Because the problem is that I only be able to see this menu when I start to edit with a post template of example (of the own theme), not with a new post.