If you're running a MediaWiki 1.35 with PluggableAuth and LdapAuthentication2, there's two ways of supporting login for LDAP accounts and local accounts.

In LocalSettings.php, set either

$wgPluggableAuth_EnableLocalLogin = true;

or

$LDAPAuthentication2AllowLocalLogin = true;

They have slightly different UI, but work pretty much the same from a login perspective. However, the LDAPAuthentication2 variant does not support local account creation.

So, if you're getting an error message along the lines of "The supplied credentials could not be used for account creation" when trying to register a local account on your MediaWiki instance, you may need to set $wgPluggableAuth_EnableLocalLogin = true; in your LocalSettings.php.