The Client Organizer is only available as the last program update in each year, and for the 2021 Desktop software, the final update that allowed this was version 36.08.
To access the client organizer, log in as Admin first. Then ensure you are in the 1040 Individual package.
Next, click Reports from the top and select Client Organizer.
Solution Articles:
Removing SSNs from Client Organizers
"(757) No pages were selected..." when printing Client Organizer