Homepage Sidebar problem

Hello,

I have my homepage set to the recent posts page, which is how it is supposed to be.
The problem for me with this theme is that it does not show the sidebar on the homepage. I managed to add the sidebar to the homepage, but because the latest posts are displayed on 3 columns instead of 2, the 3rd column is covering up the sidebar.
How can i get rid of the 3rd column. How can i make the grid of the posts to be displayed on 2 columns instead of 3?

This is the page: https://filologisme.ro/

I need this only for the desktop version.

Any help is greatly appreciated.

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