Thank you for your explanation.
I saw this elsewhere in the forum as well but found it too complex to try but now I have tried and it works but it created 4 posts because I have 4 different tags.
But then I saw this on another forum post here Updating or posting a Wordpress post with multiple tags created with an Iterator module - #8 by EaZyGreen and I tried connecting the source module of the Array aggregator to the Iterator and now it works just fine.
Thanks for your help.