It is understood from your original question that you want to use an image from the Fluent Help manual.
If you are using an academic license (and not a free student license), and using it for only academic purposes, (and not for any commercial purpose) you can use the image from it if you are citing it using the format mentioned in the link I shared earlier:
General documentation citation: Ansys® [product name], release number, help system, [book and chapter reference name/numbers], ANSYS, Inc.
-Aniket
How to access Ansys help links
Guidelines for Posting on Ansys Learning Forum
You are navigating away from the AIS Discovery experience