Autodesk external developers may need or want to use our product icons on their apps for a cohesive design, however, using Autodesk product icons without written expression of permission is not recommended.
So if you are developer who is using or planning to use, you need to submit the permission to Autodesk.
Autodesk Permissions Workflow found here.
In case if the link breaks - https://autodesk.tap.thinksmart.com/prod/Portal/ShowWorkFlow/AnonymousEmbed/cf050d55-075d-4da3-9423-db7e85ced572