Creating a Facebook Ad Account Sandbox account and unlocking ads_read - (AKA: Getting through the getting started tutorial from facebook)

In case anyone else is having the same problem i was, I feel it's appropriate to post how I managed to get the right token.

First off there is nothing wrong with the tutorial code here:
https://developers.facebook.com/docs/business-sdk/getting-started/#js

The hard part is to find the right token and give it access to make the calls used in the tutorial.

Assuming that you already have managed to create a Sandbox Ad Account you need to connect it to your business account here:
https://developers.facebook.com/apps/[APP-ID]/marketing-api/tools/?business_id=[BUSINESS-ID]

On this page there should be 4 buttons next to where the sandbox account is listed. One of them is a key with the caption "Get Access Token". This is the WRONG access token. (If anyone can elaborate on how/why please feel free). In order to get the access token you need to run the "Getting Started" sample you will need the ads_read permission.

Among the 4 buttons there should also be a suitcase with the caption "Connect to Business". If you do not see this button it either means you have no business or that you haven't attached a system user to your business (I think).

If the button is not there
Go to: https://business.facebook.com/settings/system-users?business_id=[BUSINESS-ID]
Create a system user and connect it to your App. Don't forget to set the permissions for that user.

If the button is there
Click the button and select your system user in the dropdown. Then go to:
https://business.facebook.com/settings/system-users/[SYSTEM-USER-ID]?business_id=[BUSINESS-ID]

And click the Generate New Token button. Again don't forget to set the permissions for the token.

It may seem like a silly issue but it cost me almost a whole day myself so hopefully this could save someone else the time.

EDIT: I came across an access token debugger which could prove helpful to others with access token problems:
https://developers.facebook.com/tools/debug/accesstoken/