Riga to Poland

Hi, 

I’m currently in Riga and am looking to get to Poland. I don’t really plan to stop in Lithuania. I’ve tried to plan my journey on the app but no stations appear. As far as I’m aware, some stations for the Baltics aren’t available so I would need to add manually. However, when I have googled routes the only options that come up are via buses. I’d obviously like to make the most of my pass if possible so would rather a train. Does anyone know if it is even possible to get to Poland via train from Riga and if so how? Also, would it be included on my pass (I have a continuous global pass)? 
 

Thanks in advance ☺️