Yes. It is possible to connect both the Pegasus J2i and the Pegasus R4i. These will be detected as a device in macOS disk utility, both the Pegaus R4i and J2i should automatically be mounted in the macOS, because they arrive preconfigured. If not simply open disk utility, highlight the disk, and click the mount.
The Pegasus R4i will managed via the Promise Utility. Please click on the >>link<< to download the utility.