If that box is checked, PW will track the claim as a paper claim instead of an electronic claim. When running the Outstanding Claim expert, if you choose 30-999 for electronic claims, but 45-999 for paper claims, it will be tracked within the paper claim criteria.
When choosing payer ID numbers, sometimes there isn't one for a specific insurance company. If submitting claims through Carestream, you have the choice to enter a payer ID of 00004 which will send electronically to the clearinghouse, but the clearinghouse prints and mails the claim for you. This is the instance when this checkbox should be checked.