Sims 2 - can we download and play on two computers simultaneously?

Hi, 

My and my sister wanted to buy the Sims 2 pack but we have never used origin or any other app. 

Do you know if we can create just one account and buy just one sims package  and then download them on two different computers to play simultaneously?

Is it possible? Or do we need to buy two separate packs? 

Also, is it possible to play the sims 2 downloaded from origin or ea app offline? 

I would appreciate help 🙏