There's a very easy-to-use integration for Harvest that shows up in the Desktop web app version of Asana. Once you activate Harvest in your Profile Settings, you will see a stopwatch icon on every task beside the "more actions" menu. Clicking this will open the Harvest time tracking screen. Video Walkthrough:
- Log into Asana and click your profile picture to access your profile settings
- Click the "Apps" tab
- Turn the Harvest Time Tracking app "On"
- Open up a task and see that there's a ⏱️ icon
- Click the ⏱️ icon to open the Harvest Time Entry screen (you might need to log in the first time)