Hello,
It's been over a month now that, thanks to your advice, I started using the Blocksy theme (free) along with some other builders like Kadence or Stackable.
Now, however, I have a problem, well actually two.
Trying it locally, in 2 sites I installed Blocksy, one is the website I was working on, and in the other one I've installed the starter site "Blocksy News" because I had seen this template (that I want to copy) on the Blocksy site and liked how the sidebar was structured. The other site is just the site I was working on.
First, in the sidebar, in the posts list, all my links are underlined and I don't know how to remove the underline.
Besides this, I wanted to insert the "categories" widget as I see it there in the Blocksy News template.
I open the widget in the sidebar, copy it, go to the sidebar widget on my other site, paste it, but it doesn't work.
So I went to find out why.
Basically, the widget is a Legacy Widget, so I simply tried to "create" it on my site. I added the legacy widget in my sidebar but when I go to configure it, among the choices in the configuration, the list of categories does not exist.
What am I missing?
Thank you in advance

Honestly haven’t extensively used it before but at the first thing that comes to mind is, have you tried going through the plugin’s settings and enabling an option for that sidebar or maybe choosing it from a dropdown ? Usually works.
https://i.redd.it/igwv93igilhd1.gif