How to generate ${CATTLE_ACCESS_KEY} ${CATTLE_SECRET_KEY}

I run rancher v2.6.4 on rke cluster and what to call APIs as show here : How to create a cluster in Rancher v2.x using the Rancher CLI or v3 API | Support | SUSE

The problem is that I found no way to declare (or to get) the variables ${CATTLE_ACCESS_KEY} ${CATTLE_SECRET_KEY} with the GUI.
Can you help please
Crdt