Unfortunately, it isn't currently possible to print your digitally-filled answer key, but is something we hope to add in the future.
In the meantime, you can export a list of the correct answers. From your course dashboard, select 'Edit Answer Key' then 'Import/Export' button in the top right-hand corner. Highlight the answers in the text box and copy them to a text document.
Please note: if you completed your answer key online, you do not need to print and rescan the answer key with the completed test sheets. The test sheets will automatically be marked against the digital answer key once uploaded.