Yes, you can resume. Click on the incomplete download and select 'Find sources now'. Sometimes it will restart but I've had some that hang there forever. It's been as quick to start again from scratch.
Hope this helps.
Hands-on: Samsung Galaxy S8 review
1995-2015: How technology has changed the world in 20 years
Samsung's beautifully designed Galaxy S8 makes for better VR experiences too
47 iPhone camera tips to help you take better photos
Synology invites you to visit them at Insomnia on 26th – 29th August. Book your tickets now and visit Synology.