how to rec from a fireface802 source AES in audacity

after 4 hours of stuck and that I take slaps from this board ( fireface 802 ) I kindly ask here STEP by STEP how I have to do to :
rec from a source fireface 802 AES EBU to audacity.
I kindly recommend STEP by STEP
always thanks

OSX el Capitan

Nome modello: Mac mini
Identificatore modello: Macmini6,2
Nome processore: Intel Core i7
Velocità processore: 2.6 GHz
Numero di processori: 1
Numero totale di Core: 4
Cache L2 (per Core): 256 KB
Cache L3: 6 MB
Memoria: 16 GB
Versione Boot ROM: MM61.0106.B0A
Versione SMC (sistema): 2.8f0
Numero di serie (sistema): C07JL412DY3H
Hardware UUID: D167EB13-9A32-5A7A-9894-E4FC9032FEB5

I think I’d try the FireWire 400 connection first. You can get an adapter which goes from FireWire 400 to the FireWire 800 connection on the back of your Mini (assuming a modern one).

Connect them and go into the Apple System Preferences and see if you can find the 802.

Apple (upper left) > System Preferences > Sound > Input and see if the FireFace 802 appears. Once you got it that far, make some music and see if the Preferences Panel input level meter responds. Audacity gets it’s sound from the computer, not the device. So if the Mac is OK with it, then start or restart Audacity and go on to the Audacity device toolbar.

Where do you lose it?