For purchased content packs, we recommend that you download and install all purchased content directly from the CTA5 content manager. Please see this FAQ for the installation method:
https://kb.reallusion.com/Product/53119/How-do-I-install-content-packs-if-I-have-already-purchased-CTA5
For the content files that are saved in Custom, you can directly go to Content Manager Settings > click "Smart Import Custom Content", select the custom content folder and it will automatically sync all content files stored in the folder.
CTA4 Default Custom Content folder path:
C:\Users\Public\Documents\Reallusion\Custom\Cartoon Animator 4 Custom