caja software package provides file manager for the MATE desktop, you can install in your Ubuntu 16.04 LTS (Xenial Xerus) by running the commands given below on the terminal,
$ sudo apt-get update $ sudo apt-get install caja
caja is installed in your system.
Make ensure the caja package were installed using the commands given below,
$ sudo dpkg-query -l | grep caja *
You will get with caja package name, version, architecture and description in a table
| Distro | Ubuntu 16 04 lts xenial xerus |
| Section | Utilities |
| Package | caja |
| Version | 1.12.7-1 |
| Description | file manager for the MATE desktop |
| Sub Section | Utils |