You can filter blog posts in the Divi blog module easily with the Divi Filter.
Click on the grey gear icon to access the Button Settings (on the button, that you want to filter with). You can also use images, or any other element to trigger the filtering. It doesn’t have to be a button module.
Go to Advanced → CSS ID & Classes → CSS Class. Here you add the df-button class.
Additionally add any category that you want to filter with that button like that: dfc-[blog-post-category]
The category is the category of the blog post.
The category "Lifestyle" would be dfc-lifestyle. Everything in lower cases.
Screenshot from WordPress Dashboard in Posts
Buttons have to be in a separate section, than your filterable elements. Or you add the df-buttons class to your button row (Premium features).
Click on blue gear icon to access the Section Settings.
Go to Advanced → CSS ID & Classes → CSS Class. Here you add the df-area df-post class.