To store the the courses in the Conten Repository, a content-folder with name and label "DotLRN Catalog" was created. Also the previously created content_type is registered to the folder, by calling to the same after-install apm-callback-proc as follows:

set folder_id [content::folder::new -name "DotLRN Catalog" -label "DotLRN Catalog"] content::folder::register_content_type -folder_id $folder_id -content_type "dotlrn_catalog"