To display diagrams inside a standard or custom object the managed package integration must been installed into a Production Org, the Org has been connected to a Space in Elements (Free or Pro), and user provisioning has been setup so that Salesforce users have a user account in Elements.
A Lightning component "ElementsDiagramView" is installed with the Elements Catalyst managed package. This allows any Salesforce user to view Elements process diagrams in a Lightning page for a standard or custom object.
Installing Lightning Component and setting diagram to view
The Lightning Component is called "ElementsDiagramView" and is accessed from the left panel. Drag it onto a Lightning page. The screenshot below shows it in a separate tab called "Process Diagram". Click on the component to configure it in the right panel. The DiagramID for a process diagram can be found in the DETAILS tab in the right panel of the diagram or in the URL. For example: 5be3358ecb4a70051575979b in the URL below https://diagram.q9elements.com/diagram/5be3358ecb4a70051575979b
Use Component Visibility to make different process diagrams visible based on the value of a field on the record - e.g. record type.
Setting access rights
The users need to have access to the process diagram. Set the access rights in Elements. Go to the maps list and in the SHARE tab in the right panel either select "All users can view map" or give individual users view rights.