If you want a plug and play option, use the link below for the Hifiberry Roon ready .img. Just write it to a sd card, plug it into the Rpi, turn it on and Roon discovers Hifiberry Digi+ on the network. No other installations needed. The .img is also auto updating when a new version gets available.
The blog post is old, but the link takes you to the latest .img version.