Thank you for contacting Adobe Captivate Prime Team.
If I understood the issue correctly you wanted to create a Catalog and let an outside client see the courses through it.
We need to register the client as a Learner in Captivate Prime account first. Then you can create a Catalog and share it with the Client only if you do not want your client to see the other catalogues.
You can set this up in the Catalog section using "share internally" option.
Kindly let me know if any further assistance is required. Hope to hear from you soon.