Enable GPU Hardware acceleration on Media Encorder

Hello everyone and many thanks to whoever will give me an answer to this.
I'm working on two machines, both Mac OS. I've also seen hundreds of tuts on youtube and read many documenation here, on Adobe site... But I can't solve this.

The fact is: even if After Effects and Premiere Pro use the GPU while working, when I try to export my file using Media Encoder the encoding is set on software only. If I try to change to Hardware Acceleration a pop up is shown where it says that my hardware can't support the GPU acceleration. But, I've seen a guy on youtube which have the very same hardware of mine, and it works for him. I really can't figure out what am I doing wrong.

In attachment my hardware and my settings on Premiere, After and Media Encoder.
Thank you,