Jira Software Rest API setup

I have a project that has a splunk site and want to access our Jira site using the Rest API. We’ve created a user id to be used for the interface.
I can’t figure out a way to grant that user id project permissions to utilize the REST API with that user’s credentials or how to create an OAuth token to access the API. Can someone provide some direction? I would rather use the OAuth token to grant it access since it’s more secure.