There is no need to create the folders before performing a Public Folder migration, unless migrating more than 20 GB of data to Exchange Online, in which case, BitTitan support will need to provide scripts to create the IPF.Note folders and additional public folder mailboxes before migrating. MigrationWiz will create all folders from the root to the folder being migrated. However, only the folder being migrated will have proper permissions set and will be mail-enabled (if appropriate).
One thing to note is that the source and destination folder type must match. This means that if you are migrating a Contact or Calendar folder, then the destination folder has to be created as a Contact or Calendar folder. Folders other than IPF.Note (Email) folders can only be created correctly through EWS, which is what MigrationWiz uses for migrating public folders. If the folder is not of the correct type, then no items will be migrated into it (e.g., mail items cannot go into a Contacts folder, and vice versa).