I sent an email to prospective Ph.D advisor asking for a scholarship in his university and position in his research group. His reply was only "please, apply mentioning my name", I didn't understand if he accepted me or not!
As far as I can tell, he has neither accepted you nor rejected you. Depending on your department's system, he will probably read only the applications that mention his name, so he wants you to mention his name so that he'll remember to read your files. If those are good compared to the other files, he might accept you. Otherwise he might not. It's too early to tell.
You don't mention in which country the professor is located, but it sounds like you may have misunderstood the application process.
His reply of "Please, apply mentioning my name" seems to indicate that he does not have direct responsibility for accepting Ph.D. students. This varies from country to country, but in the USA applications are made to the department as a whole and professors do not have the authority to admit you on their own. (Of course, they can urge the appropriate committee to accept your application if they choose.)
It seems that you hoped to be offered a position and scholarship on the basis of a single e-mail, without having submitted an application. This is not how academia works (possibly unless the prospective advisor already knows you, and usually not even then). Positions are competitive, and there are proper channels that you need to go through.
In any case, I would say that his reply is neither positive nor negative; certainly it is not either an acceptance or a rejection. I recommend that you look on the department's website for application instructions, and follow them. After you apply, if you are accepted, you might contact this professor again and ask if you can join his group.