Anyone can tell me what to do about this? it happens when i try to add my first account in the settings

"Could not start the account wizard. Please make sure you have AccountWizard properly installed".

First off a few details to help with providing accurate answers: What OS are you using? How did you install KMail?

Checking the packages in (K)Ubuntu 18.04, I see there is a separate "accountwizard" package that you may need to install (should be named similarly if you are using a different linux distro).
This package should be included in the "kdepim" metapackage which should pull in all of the other necessary components. While you may install the various packages in the kdepim metapackage individually each package that you don't install reduces the available functionality.

If installing packages using KDE's Discover, it only shows applications and so won't list the "accountwizard" or "kdepim" packages. I assume installing Kontact should pull in the full kdepim suite and all necessary components, but I don't know for sure. Installing using your distro's package management tool would allow you to install the specific packages you'd need.