wordpress subcategory problem

For securiy purposes i have installed wordpress within a subcatgory and moved the wp-config file to an upper category.

Now my website url is e.g. myurl
and my wordpress adress e.g. myurl/subcategory

So in Frontend everything goes by my url e.g.
http://blog.url.at/index.php

But in Backend e.g.
http://blog.url.at/subc/wp-admin/

If i want to download a file with the plugin then it wont work because the subcategory will be included.
Wrong: http://blog.url.at/subc/?wpdmdl=20&_wpdmkey=55e33413124e2

If i remove the subcategory from the link name than it works.
How to configure that correct so the subc will not be used??
Right: http://blog.url.at/?wpdmdl=20&_wpdmkey=55e33413124e2

Thx!

https://wordpress.org/plugins/download-manager/