How to downloads and media files protection?

Hi All,

can you please somebody write me step by step how can I set the downloads and media files protection?
I use the latest Membership plugin 3.0 and cannot find the solution.

I do this:

Create 3 Access Levels:
- Strangler - read the all default post, but cannot read and write comments
- Default membership - free subsription: read the all default post, To be able to read and write comments and can download defalut media
- Premium - this is inactive now

In the Options menu I set the Default membership to the Protected groups in Download / Media Options. And I set Masked download URL: http://wordpresskezdoknek.hu/premiumletoltes.

I edited the Default membership level int the Access Levels. And I add the comments and the downloads widget to the positive rule.

I edit the downloadable media in the media manager and set the default membership.
I insert the downloadable file to a post this method: http://wordpresskezdoknek.hu/premiumletoltes/Membership-Docs1.pdf

But the user who is the member of the default membership cant download the file.

Please help. What should I do?
Thanks,
Robert