The "IB-3780-C31" hard drive enclosure from Icy Box supports up to 8 hard drives or SSDs, each either 2.5" or 3.5" in size. The storage capacity per HDD depends on the particular hard drive that is installed in the enclosure and not on the enclosure itself. There is no specific storage capacity limitation by the enclosure as long as the HDDs fulfil the SATA interface and the corresponding sizes (2.5" or 3.5").

The manufacturer only confirms support for Windows and macOS.

Yes, if the CMR drives are AHCI (SATA)...