Newly installed site and problem with Admin Control Panel

[5404]

Hey.
Today I started testing Mysidia Adoptables 1.3.2 on my site on free hosting... And...
I installed it about 5 times*. I did some stupid mistakes. But then I installed script (I hoped) properly but AdminCP didn't work...
And I installed again - looking at this tutorial carefully...

But again AdminCP isn't working.
/admincp/ looks normal and wants me to log in. Then it redirects to /admincp/index - which don't exist.
When I manually change url to /admincp/index.php or any other .php file from /admincp I get blank site. (Only with hosting footer and (blocked for me) ads.)

I just don't know what went wrong. x.x
I don't know php (only basis) so I can't find where's the problem.
Any ideas what I should check/change/add etc.? .-.


*Yes, each time I deleted tables from database or used different prefixes. And I deleted all files from site directory and copied them from .zip again.