Because you can use Interrail in your country of residence only on 2 of your travel days:

https://www.interrail.eu/en/interrail-passes/what-is-interrail/travel-your-own-country

You can still use your 2 travel days but you'll need a separate ticket to/from the border.

Thank you. 
Can I exchange the pass into another pass, that makes more sense? To just travel into and out of Poland ?

You can exchange the pass if you haven't used it yet. If you have activated it but with a future start date, then you first need to cancel the activation. Exchange is not possible anymore when the validity period has started:

https://www.interrail.eu/en/interrail-passes/ordering-info/refund-exchange-policy

Hey everybody!

I am trying to figure out how to get a physical map of the route. I can plan better with my hands on a physical map.

Thank you,

Rue

I believe this one is well known : https://www.europeanrailtimetable.eu/rail-map-europe-3rd-edition-2nd-revision-folded-1111-p.asp (maybe you can get it on Amazon to avoid postage fees from the UK)

Otherwise I’d suggest using https://www.openrailwaymap.org/

I really love this website as the overview is clear.