Before I could think of the solution, I would like to understand the problem statement currently.
When the user (Requester) visits the visitor page of Freshservice, you want to show a button.
As the user clicks the button, you want to show a new incident page, where an agent can associate an incident to an asset.
My understanding of the above has a flaw, hopefully, you can help me understand better → Usually, requesters report an incident, and agents associate the incident to the asset. But here you suggest the requester should be able to see the “associate with assets” page which currently only agents can access. Am I right?