Read a Linux Disk in MacOS?
Solution 1:
Linux is very flexible when it comes to filesystem formats and disk setups.
The most common problem you will encounter is the most popular filesystem for Linux: ext4, which is of course not supported by Apple under macOS.
To gain access to these filesystems, you need either OSXFuse and a slow implementation of read-only access (eg ext4fuse, eg via macports or homebrew) or the commercial Paragon ExtFS.
A great many more exotic filesystem setups cannnot be dealt with from within macOS.
A more convoluted but more flexible solution method might involve either booting your Mac into Linux and copy the files or using a Virtual Machine that runs Linux to extcrat the files.
Virtual Box usually can handle USB (provided the settings are right) and most Linux installations from within there as well (again: settings). The Linux installation needs support for the actual filesystem (mainstream distributions usually do.) As the RAID was 1 aka mirroring, one of the disks should then be readable.