Can't launch UE 4.26.1 on mac 10.13.6

Hi – I’m trying to run Unreal Engine on mac 10.13.6. I’ve managed to install successfully and the Epic Games launcher runs fine – but when I click ‘Launch Unreal Engine 4.26.1’ all that happens is my mac switches to the last application used (e.g. it will just go to the Finder). When I go back to Epic games launcher, nothing has happened i.e. there is no error code, and Unreal Engine hasn’t launched. I’ve tried re-installing but the error is exactly the same. I can’t find any documentation on how to install and run on mac (e.g. whether I am targeting the right platform – I’ve tried iOS and Android but doesn’t seem to make a difference).

Thanks for your help!

System info:

Model Name: Mac Pro
Model Identifier: MacPro6,1
Processor Name: 6-Core Intel Xeon E5
Processor Speed: 3.5 GHz
Number of Processors: 1
Total Number of Cores: 6
L2 Cache (per Core): 256 KB
L3 Cache: 12 MB
Memory: 32 GB
Boot ROM Version: MP61.0124.B00
SMC Version (system): 2.20f18
Illumination Version: 1.4a6
Model Name: Mac Pro
Model Identifier: MacPro6,1
Processor Name: 6-Core Intel Xeon E5
Processor Speed: 3.5 GHz
Number of Processors: 1
Total Number of Cores: 6
L2 Cache (per Core): 256 KB
L3 Cache: 12 MB
Memory: 32 GB
Boot ROM Version: MP61.0124.B00
SMC Version (system): 2.20f18
Illumination Version: 1.4a6
Model Name: Mac Pro
Model Identifier: MacPro6,1
Processor Name: 6-Core Intel Xeon E5
Processor Speed: 3.5 GHz
Number of Processors: 1
Total Number of Cores: 6
L2 Cache (per Core): 256 KB
L3 Cache: 12 MB
Memory: 32 GB
Boot ROM Version: MP61.0124.B00
SMC Version (system): 2.20f18
Illumination Version: 1.4a6
Graphics card: NVIDIA GeForce GTX 1080 Ti