Mount ext4 filesystem on macOS

1) Install ext4fuse.

brew cask install osxfuse
brew install ext4fuse

2) Select partition.

diskutil list

/dev/disk3 (external, physical):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *3.0 TB     disk3
   1:       Microsoft Basic Data                         3.0 TB     disk3s1

3) Mount.

sudo ext4fuse /dev/disk3s1 ~/Disk -o allow_other