Where can I get information about this for obtaining a DOA?

Below are two useful links regarding applicable regulations, guides and information needed for DOA processes:

• DOAS NO EASA (ESA competence):
  https://sede.seguridadaerea.gob.es/sede-aesa/catalogo-de-procedimientos/aprobación-de-organizaciones-de-diseño-no-easa
   
• DOAS EASA:
  https://www.easa.europa.eu/domains/aircraft-products/design-organisations/design-organisations-approvals