you should treat ktor as a simple point to get your data. How your UI reacts on it is up to you, just like any other library you might use to do the job.
A simplistic approach would be:
• Invoke an action that loads data (e.g. click a button)
• Show loading dialog
• Trigger backend call with your favourite http client (e.g. ktor)
• When result is success or error, hide the loading dialog.
How you get the result passed back is up to you. You can use whatever you want for it, but it will not happen magically out of the box. I suggest using this wonderful website called Google to Google your favourite platform to work on, learn about patterns to make backend calls and showing loading dialogs and then substitute the http library for ktor