You might have better luck dual booting your Mac with Linux thb. It sounds like you are trying to run the stock grin miner. Maybe try finding a different one that supports MacOS. Based on your errors, it looks like the miner does not have access to opencl compute libraries for your GPU. Might just not know where they are since MacOS is a bit different.
From what I remember with the stock miner you have to build the OpenCL plugins for AMD.
Personally I use an alternative miner, but you might not have a choice with MacOS.
Maybe give this a try.
Hope this helps,
Macker