How to create a client secret from the Microsoft Partner Center?

Question

I'm trying to use StoreBroker to manage submissions automatically for my UWP app.
In order to do that, I need a TenantId, a ClientId and a ClientSecret.

I have the TenantId and the ClientId from the Microsoft Center website but I have an error when trying to create a new ClientSecret:

The Support link forwards to a 404 page.

I'm following this documentation: https://github.com/microsoft/StoreBroker/blob/master/Documentation/SETUP.md#authentication