In Google Chrome open the site developer.nintendo.com/register

Click on Create New Account
 

Click on Review Application

In a minute we will receive an email that our registration continues further:

Click on the link to activate the registration:
 
A page with a password will open:

In Google Chrome open the site developer.nintendo.com/web/development

and enter Nintendo Developer ID and the password just made:

 
Let's read the terms of use:

Click on the Submit button

We will see a message confirming that everything is fine:

Above in the picture it is written that if we want to get all access Nintendo Developer Portal, then we need to click on the link here.

I clicked on the link and a page opened with the text: Not Found
That's okay.

The link was to get all access Nintendo Developer Portal

Question: Why do I need all access to Nintendo Developer Portal?

Answer: All access will give you the opportunity to download from Nintendo Developer Portal:
• library Nintendo Switch C++ SDK
or
• library Nintendo Switch Unity SDK
To start writing a game

Read: How to get full access to Nintendo Developer Portal to download the Nintendo Switch C++ SDK or Nintendo Switch Unity SDK library and start writing the game