If you're determined to disregard the sound advice against the use of XML::Simple, you can do

Win8 Strawberry 5.8.9.5 (32)  Mon 04/19/2021  5:08:21
C:\@Work\Perl\monks
>perl -Mstrict -Mwarnings

use Data::Dumper;

my $got_data = {
         'ref' =>
{
 'abc_sia_%version1.ref' =>
{
 'func' => [
            {
             'envname' => 'test01',
             'objectdir' => '/home/pv66',
             'base' => 'default_771'
            }
           ]
}
}
};

my $want_data = $got_data->{'ref'};

print Dumper $want_data;

^Z
$VAR1 = {
          'abc_sia_%version1.ref' => {
                                       'func' => [
                                                   {
                                                     'base' => 'defaul
+t_771',
                                                     'objectdir' => '/
+home/pv66',
                                                     'envname' => 'tes
+t01'
                                                   }
                                                 ]
                                     }
        };
[download]

It looks like the hash reference you want is just the value of the 'ref' key. See also perldsc.