I’ve activated the Active Directory Integration plugin to assist with WP account creation, and set the proper Domain Controller (dc.company.int), Base DN (OU=Users,OU=_XXX,DC=company,DC=int), account suffix (@company.int), default email domain (company.com) and login sync settings.
Checking wpDirAuth’s settings using the admin account again, i think the problem was “userPrincipalName” in the Account Filter field that defaults to “samAccountName”, as users use their account name to log in.