RapidMiner - aggregate operator issue

Hi, i'm following the rapidminer data engineering course, im using an ubuntu laptop with jdk version >8 & have mentioned rapid miner version above. 

Here is the screenshot of the error i'm facing - i encountered it while i was following the generate attributes chapter

I also tried to use market place to find relevant plugin but i get the msg that nothing compatible found 

Please let me know if anyone has any ideas about this.

Thankyou