Go to tiendanube.com and click on Access my panel (Acceder a mi panel).
Log in with your store account on Tiendanube.
Once inside your store panel, go to the left side menu and select Settings (Configuración).
Under the Payment methods (Métodos de pago) section, scroll down until you find Ecart Pay.
Click on the Activate (Activar) button.
Accept the terms to integrate Ecart Pay into Tiendanube by clicking on Accept and start using (Aceptar y empezar a usar).
Click on Start setup (Iniciar configuración).
Log in with your Ecart Pay account.
You will see your active session; make sure the email address matches the one for your store on Tiendanube.
Click on Continue (Continuar).
A notice will appear confirming that the integration was successfully configured.
Click on Go to Tiendanube (Ir a Tiendanube) to return to your store panel.
In your Tiendanube panel, go back to Settings > Payment methods (Configuración > Métodos de pago).
You will see that Ecart Pay is now installed and activated.