This members-only tutorial provides the steps to add a User-type of custom field using Advanced Custom Fields for a Custom Post Type and output the linked user's display name, avatar/custom image, bio description and a link to that posts authored by that user for each CPT item on the CPT archive.
Step 1
Create a ACF field group having a User-type of field named say user.
Leave the Return Format as User Array.
Set the group to appear for your CPT (staff in this example).
Step 2
Edit your CPT items and select a user for each.
Step 3
Time to define some custom functions that returns
the specified key from the user field's returned array
URL of the avatar/custom image from the ID of the selected user for the post (CPT item, in this case)
Install and activate a code snippets plugin like WPCodeBox.