501 Error when trying to install Unreal Engine

This error is caused by the Epic Games Parental Controls. To resolve this issue:

1. Disable the Parental Controls on your Epic Games account.
2. Then install Unreal Engine.
3. Afterwards you can re-enable Parental Controls.

Instructions to disable parental controls can be found here: https://www.epicgames.com/help/en-US/c-Category_EpicAccount/c-EpicAccounts_ParentalControls/how-can-i-change-my-parental-controls-settings-a000085597