I see a number of problems.
First forget this '\' stuff! That is ancient DOS. Modern Windows command line is NOT DOS and it works fine with '/'. In your code always use forward slash ('/') instead of backslash ('\'). This amoungst other things avoids the need to "double escape" the backslash. Again, forget this '\' stuff!

my $base = 'D:\Some\Specific\Folder\Archive\\';
# should be:
my $base = 'D:/Some/Specific/Folder/Archive'; # a path to a directory
or
my $base = "D:/Some/Specific/Folder/Archive"; # a path to a directory
# do not put a trailing '/' or '\' on a directory name
# this is not needed and can confuse the shell
# pre-pend a '/' when you expand the path
my $new = "$base/$extra_path";
[download]

Your triple loop over $year,$month,$day is truly bizarre.

my @files = glob qq($base\\Gridfee0?.7z\\Gridfee?\\invoic_
+b2c_$year$month$day*.txt);
[download]

What are you trying to do there? I don't quite "get it".

I am curious as to why you are using .7z suffixes? I like 7z. It generates .zip files faster which use less memory than the MS zip program does. These .zip files generated by 7z are compatible with Windows .zip. I've never used the .7z specific format because the .zip MS compatible format appears to be just fine for my applications. Again, if 7z makes that .zip it will be smaller than what MS does, be generated faster and yet be compatible with MS .zip.