A help desk technician is installing an application for a user who is in a...

The CompTIA Tech+ Study Guide explains:

“Remote support software allows technicians to connect to a user’s computer from another location, troubleshoot issues, install applications, and perform updates without physically being at the same site.”

Additionally, the review question section confirms:

“You are setting up a technical support help desk for a new app. What type of software should you get to help the technicians fix problems more effectively?

Answer: Remote support.”

Thus, the technician in another state uses remote support software to perform the installation.

Verified Reference:

Chapter 5: Software Applications — “Remote Support Software” (pp. 347–348).