You need to put the user stories in a different project if you want to do this natively.
If a user has "create" in a project, then they can create issues. That's it, there's no support for restricting by issue type
Your options are basically:
The first couple of options are easy to bypass, as they won't stop users using REST or add-ons or quick create or or or. The validator option will work in all cases, but has the problem that it will really annoy your users as they've already put data in which can then be lost when they're told they've got it wrong
(Note that this is generally a monumental pain when people do set it up)
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