Spreadshop, how?

Oke, I just want to add more products and now I see that spreadshirt doesn’t work anymore with this plugin. Spreadshop should be the sollution, but where to sign-up? I’m really lost now…

Can’t I add products with https://partner.spreadshirt.nl/ anymore??? Why? Maybe there is another solution?