Start from the TOP of the guide you linked to… especially the REQUIREMENTS section. You haven’t done that part, so your domain is not ready to begin the transfer process.
I can see the nameservers have propagated now. I have followed up in the ticket you opened, but it looks like everything is now working as expected and tiendabymatic.com is in the process of transferring. If you come across any other issues, you can follow up with me in that ticket.