A number of things are changing due to the transition from the LoRa Developer Portal to the new KPN Things Portal. You will have to create a new account and the devices from the LoRa Developer Portal must be transferred. Devices cannot be added in both Portals.
To support you as well as possible in the transition to the KPN Things Portal, we have created a Coming from the LoRa Developer Portal page with tips. Besides the tips and information on this page, feel free to create a topic with your questions. I am happy to help you!