I do not know of a solution to show a popup on a link, but dependent on your use case (especially the number of links and it's representation on the page) you may choose to hide the link with a macro. That is the user won't see the link (or anything that is inside) according to their permissions.
There are a couple of plugins you may choose from to get this functionality:
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Hi Community! me again 🙂 If you’re a marketing team using Confluence, we want to hear your story! How did you start using Confluence? What are your use cases? What have been some of the benefits?...
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