Request Entity Too Large (php Error 413)

After my provider changed some path on my hosting account I needed to change the path of the download rooth folder.
Going to /wp-admin/admin.php?page=file-manager-permission-system I changed it and clicked “save” resulting in the following error:

Request Entity Too Large
The requested resource
/wp-admin/admin.php
does not allow request data with POST requests, or the amount of data provided in the request exceeds the capacity limit.
Port 443

According to my hoster this error accurs when I try to post s.th. above 64 MB which is the server limit.

I guess that the form does just post kb and not MB. So any advice on this?

I also tried to change the path directly in the database in “fmp_permission_system” – however this just resulted in not displaying the download manager at all.