WooCommerce download link NOT WORKING

i administer an ecommerce website using the woocommerce plugin located at https://www.stkgroup.com.ar

need to publish downloadable products with no luck so far. when i make a test purchase the link shows up but nothing happens, it just redirects to the home page. examples:

https://stkgroup.com.ar/?download_file=480&order=wc_order_56afb5e832797&[email protected]&key=d7811f31686b77d92faa8407055d7901

https://stkgroup.com.ar/?download_file=480&order=wc_order_56afb5e832797&[email protected]&key=373ffaf1bf7342cf066f2b5b71ad3251

could someone please test it and help me out? this is the test product link:

https://stkgroup.com.ar/tienda/cursos-de-baile/curso-completo-de-tango-y-milonga/

both virtual and downloadable product options are checked. tried all 3 available options in downloadable products (force download, x-sendfile and redirect only).

thanks in advance!