Thank you!
Yeah, sorry if I am making mistakes but I am quite new around here.
Actually you're right, I meant that I have downloaded the latest version of R (4.0.0).
When trying to load the library rattle, the system is telling me the following error -> Error in library(rattle) : there is no package called ‘rattle’.
This happens only with this library, I do not know if it is a problem related to the use of a Mac (Catalina 10.15.3).
Thanks in advance