How do I sign up for an account at Papaki.gr?

Reply: 

You can easily create you account at Papaki.gr by following the domain registration procedure.

Right after your domain search and registration, you are transfered to a page where you can sign up for an account or sign in, if you have already an account at Papaki.gr .

I any other case you can sign up for an account here: https://www.papaki.gr/transfer_2_en.asp