[download_page] not working

I found one error!

The plugin 404 Redirected (https://www.ads-software.com/extend/plugins/404-redirected/) makes a automatic wrong redirect from /downloads/?category=1 to /downloads.

Can I open the ?category=1 without the permalink directly?

like this?
/wp-content/plugins/download-monitor/wp-download_monitor.php?category=1

Any help?

Ok, I found the solution.

The script 404 Redirected (https://www.ads-software.com/extend/plugins/404-redirected/) causes the error.

The solution:
Uncheck Force current permalinks in the settings of 404 Redirected under option.