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You’ll need to split the categories by comma-space so that it becomes an array.
Then, use an iterator on the array so that you can process each category at a time.
Create new category using the name.
Then, if category exists, there will be an error. Handle the error by searching for the category, and resuming with the existing category ID.
Then, aggregate the category IDs into an array using the Array Aggregator.
You can then insert the array of category IDs into the tag/category field.
Similarly, this works the same way for the Wordpress Tags field.
For more information, see How to deal with WordPress errors
Hope this helps! Let me know if there are any further questions or issues.
— @samliew