Zillow Group (Z  ) CEO Jeremy Wacksman once took on a job he had never done before, and it helped reshape the company's future. The shift from desktop search to mobile real estate shopping became one of the company's biggest growth bets, Wacksman recently told CNBC.

"We were a desktop-only search engine," he said.

The pivot helped lead to Zillow's mobile launch, early profitability, and rise as a dominant real estate platform.

From Desktop Roots To A Mobile Breakthrough

Wacksman joined Zillow as a marketing executive shortly after Apple Inc. (AAPL  ) launched the App Store. Soon after, he was tasked with leading Zillow's mobile app development.

He had no experience building apps when he took on the assignment, but needed to figure out how to apply what he knew in a new area. Within about nine months, Zillow launched its first app in April 2009.

The company turned profitable by 2010, and users were looking at homes 20,000 times per hour through the app, according to Zillow. Now 20 years old, the company said it is the most visited real estate app and website in the U.S., citing Comscore data.

Growth Comes With New Pressures

The assignment fits his broader point about career growth. Wacksman told CNBC the role was not what he was hired to do, but it gave him a chance to learn and apply his experience in a new area.

He said careers are rarely a straight ladder, describing a better path as more like a "career jungle gym."

"It's often taking on new assignments that stretch you in new and different ways that lead to the most growth," he said.

The rise of platforms like Zillow helped digitize home shopping. Now a new wave of real estate platforms is trying to modernize investing itself, with some companies offering access to professionally managed rental properties through lower minimum investments.