Hi @magnushoem, thanks for your query. In order to use the Tobii Eye Tracker 4C in conjunction with the Tobii Pro SDK, this requires the purchase of a special licece and unlock file to be enabled. To receive a quote for purchase of this licence, please send an email to [email protected] with a brief description of your project specifications.
That being said, if you are happy to work with C#, then the Tobii Core SDK is fully compatible (and free) with the 4C and you can download it @ https://developer.tobii.com/tobii-core-sdk/
Sorry for the inconvenience. If you have any further queries, please don’t hesitate to get back in touch.