If you have not done so already, go to the SLATE portal and create an account.
If there is already a group which should be responsible for this cluster, and you are not a member, you should request to join it. You can also create a new group to administer your cluster (navigate to My Groups and click Register New Group).
If you do end up creating a new group whose primary purpose will be to administer this cluster (and possibly others), you should select Resource Provider as the field of science for it.
Navigate to the SLATE Portal CLI Access page to download and install the client appropriate for your machine.
To check that the SLATE client is ready to use, list the various clusters that are already participating in the federation.
slate cluster list