It is recommended that you upgrade to the latest version of Adobe Experience Manager (AEM). AEM 6.3 is no longer supported by Screens.
An AEM Screens Developer is responsible for designing and building an interactive system. Basically, a developer creates an application and creates content sequences or to develop apps or sequences which may be utilized for multiple channels.
A developer creates applications and components, works on API integrations and plugin extensions, builds player extensions, integrates analytics and performs logging operations.