I recently purtchased the Smart Controller since DJI said that it was compatible with the Mavic 3. I'm not able to connect this controller with my Mavic 3 and it's really frustration to konw that I spent so much forf this device. Is there a solution for this issue?

Depends which one you bought.  The original is not going to work.   The others just need a firmware update.  

Thanks. That really sucks though! If DJI knew it wouldn’t work, why sell it?

Hi there. Thank you for reaching out and we're sorry for the trouble. The DJI Smart Controller is not compatible with the DJI Mavic 3. DJI Smart Controller is only compatible with the following Mavic series aircraft DJI Mavic 2, DJI Mavic Air 2, DJI Mini 2, and DJI Air 2s. Thank you for your understanding and support.

Did you get the RM500 or another model number?  Only the RM500 is known as the smart controller,   the others are called the DJI RC and DJI RC Pro.