RobboLito is a very strong open-source UCI chess engine by:
Yakov Petrovich Golyadkin, Igor Igorovich Igoronov, and Roberto Pescatore

RobboLito is a UCI 'console' application, meaning that it has no GUI (graphical user interface).
There are several free programs that provide a GUI, along with a rich set of user-friendly features.

Some of the most popular free GUIs are:
winboard, chess-gui, arena (Windows) and xboard (Linux/Unix)

As RobboLito uses UCI (universal chess interface, UCI) you will need a uci-compliant user interface to play against RobboLito.
You can also use polyglot as an "UCI to xboard"-adapter to use RobboLito with xboard-compatible programs.

note:
RobboLito does not yet support: multiPV, own book, egbbs, tablebases, multiple CPUs/cores, or chess variants