How To Enable Developer Mode Enabling Developer Mode is simple: open up the Options menu when in-game. In the General tab, there'll be a 'Development mode' setting, set to a cross by default.

Developer mode allows you to sideload unofficial apps on your Roku. To enable developer mode, you need to press a specific button combination on your remote.

Windows Device Portal (WDP) is a management and debugging tool for developers. To know how enable or disable Device Portal, check this guide.