Hi @antonia.alleyne ,
Welcome to the Atlassian Community!
I might not be the best person to answer this question since Zenhub is a 3rd party software and I don't know much about it. However, there should be ways to export the issues to CSV so that then you can import them into Jira by following the steps in the below documentation page (you can switch between Server and Cloud by using the buttons on the top right corner of the page):
Also, regarding how to export the issues from Zenhub to CSV:
I hope this helps.
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