SILO url & category pages

Hello! I want to create a pseudo silo structure on my site, and need some help. I currently use the custom permalink url structure: /%category%/%postname%/ and an empty Category base field. screens: https://nimb.ws/oHCUWL
My posts use 2 post category levels ( main category (e.g. ads ) , and subcategory (e.g facebook)

so right when I publish a new post using ads > facebook as a post subcategory it creates this url: site.com/ads/facebook/article_title

My 2 issues are:
case 1) when I open a category url, e.g. site.com/ads/facebook/ it redirects to site.com/ads/facebook/article_title instead
case 2) when I open a subcategory url, e.g. site.com/ads/ , it directs to the default WP category page (which is Not editable as a normal page, e.g. https://nimb.ws/uUBAjR)

I jusy want to create some custom silo pages for each main cateogory page, and subcategory page, where I will manually select which posts should show and customize the appearance too.

How can I make sure that both the URLs for my main category(case 1), AND my subcategory pages (case 2) direct to unqiue custom WP pages instead of category pages or posts (in the same way that silo pages work)?

Many thanks 🙂

George