Hi @andredangelo. I took a look at the Arduino Due and it looks like it’s got a Cortex M3 based MCU (SAM3X8E), so it should be able to run just fine since there’s 512 KB of flash. I also found a different thread that @rtel says to that: How to Port the RTOS on the SAM3X8E .
Doing a quick search I found a old port of FreeRTOS 9.0.0 on GitHub for SAM architecture Arduino boards: https://github.com/straccio/Arduino_Due_FreeRTOS
If you want to use the Uno instead, the ported FreeRTOS library (FreeRTOS 10.3!) can be downloaded and compiled easily using the Arduino IDE: https://github.com/feilipu/Arduino_FreeRTOS_Library
Hope that helps and welcome to the community! Let us know what you’re building if you can and any tips for other beginners 