You need to have the real parser installed. Spreadsheet::Read is just a unifying frontend API to all the supported parsers. This is like using DBI without knowing what DBD is used:
your programm does use DBI; and DBI->connect decides what DBD to load. Likewise for Spreadsheet::Read.
So to parse .xslx you have to install Spreadsheet::ParseXLSX and then you do somthing like:
my $book = Spreadsheet::Read->new ("file.xlsx");
my $sheet = $book->sheet (1);
my $a3 = $sheet->cell ("A3");
Enjoy, Have FUN! H.Merijn