ExFAT with MBR should be used, but you’ll lose nearly half of the drive space. If you have 2 SC6000’s, I would opt 2x 2TB SSD’s in both and split your music, if you’d need that space.
GPT seems to work sometimes, but you’ll probably get an error.
You need to make a partition on the disk of a slightly lower value than 2TB. If you format that partition, it should work. However, you could try GPT, but I think it won’t work. I cannot test both hypotheses at the moment, as my drives are 2TB per SSD (and I’m using Windows, so not in detail familiar with MacOS disk management).