I start with prehamble that's mine is a stupid question to be avoided as much as possible and probably without any logic or sense, but I need to display the Apache authentication without crosschecking the password filled.

I would like then any user (with any username) can access to a specific server folder although they does not exists or their password is not correct.

Basically the request is to have an .htaccess file like this but without a defined list of Anonymous user and login anyway requested

AuthName "Use 'anonymous' & Email address for guest entry"
AuthType Basic
AuthBasicProvider anon

Anonymous_NoUserID off
Anonymous_MustGiveEmail on
Anonymous_VerifyEmail on
Anonymous_LogEmail on
Anonymous anonymous guest www test welcome

Require valid-user

Note: the username logged will be checked inside the php script stored inside the folder requesting authentication.