Hi @drugurkocak,
Thank you for the feedback.
Do I need to get a seperate API key and cliend id for each journal on an OJS installation?
yes, you need to get api keys for each journal, if the domains are different.
But you can try to get a global api key e.g. if you have journals like this
abc.xy/journal1
abc.xy/journal2
Then if you get the key for abc.xy you should be able to use that for other journals too.
But I haven’t tried that scenari myself.