Create Access Switch

From the blueprint, navigate to Staged > Physical > Topology and select the leaf to connect to the new access switch.
Select the leaf check box to see the operations available for that leaf (and that you have permissions for).

Note:
You can also get to the selection page from the Nodes view. From the blueprint, navigate to Staged > Physical > Nodes, click the leaf name in the table, then click the leaf name that appears at the top of the Selection panel (on the right side of the page).
Click Add access switch and enter a unique label and hostname.
Select the appropriate interface map from the drop-down list.
Enter the port channel ID min and max. (Prior to Apstra version 4.2.0, all non-default port channel numbers had to be unique per blueprint. Port channel ranges could not overlap. This requirement has been relaxed, and now they need only be unique per system.)
Enter tags (optional) to identify the role(s) of the new access switch, then click Next.
Select available ports and transformations, as applicable. The gray Add Link button turns green.
Click Add Link. The link is added to the link table.
Click Create to stage the change and return to the Topology view.

When you're ready to activate your changes, commit them from the Uncommitted tab.