A MacBook Air isn't supported. You need a desktop Mac with a discrete GPU.

Here is the list of supported Macs

iMac (Retina 5K, 27-inch, Late 2015) AMD Radeon R9 M395 1600x900 High (Mac)
iMac (Retina 5K, 27-inch, Late 2015) AMD Radeon R9 M390 1600x900 High (Mac)
iMac (Retina 5K, 27-inch, Late 2014) AMD Radeon R9 M290 1600x900 High (Mac)
iMac (Retina 5K, 27-inch, Late 2014) AMD Radeon R9 M295X 1600x900 High (Mac)
iMac (27-inch, Late 2013) NVIDIA GeForce GTX 775M 1600x900 Middle (Mac)
iMac (27-inch, Late 2013) NVIDIA GeForce GT 755M 1600x900 Middle (Mac)
iMac (21.5-inch, Late 2013) NVIDIA GeForce GT 750M 1600x900 Middle (Mac)
iMac (21.5-inch, Late 2013) Intel Iris Pro