Is it just me or did they miss the Reaper feature in the app for Grave Domain Clerics? By my reading we should get an additional necromancy cantrip (from any class) and something should mention the “two targets within 5 feet of each other” option. 

 Reaper is a Death domain feature, not a Grave domain feature. 

Bah, my mistake. No wonder it was missing!

I can't seem to access the grave domain on my character builder. Does anyone know how to accomplish this? 

Quote from Slipperyelm03 >>

I can't seem to access the grave domain on my character builder. Does anyone know how to accomplish this? 

 Grave domain is in Xanathar’s Guide to Everything. You need to either buy the book, or buy the subclass from that book.