What do I need to set up and Nordea Connect merchant account (Nordea accounts, documents, developer knowledge, etc.)?
You need to be a company registered in one of the Nordic countries (Denmark, Finland, Norway or Sweden).
You need to be a Nordea corporate customer.
In the case of certain payment methods (Dankort, Siirto) you need to have a locally registered organization and/or have a local settlement account (depending on the payment method).
You need to fill in and submit the Nordea Connect registration form and you will need to give Nordea power-of-attorney.
Depending on which integration option you choose you will require different levels of developer knowledge to conduct the integration yourself.
Even with plugins (which are the simplest way of integrating) you still need to be able to set up you eCommerce platform and understand the integration documentation.
If you lack said knowledge you will need a developer to do the integration for you.