Read a Linux Disk in MacOS?
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.