Hey everyone! I can understand the confusion here. 10.11 should run RW8, but because it’s an older OS, we can’t guarantee 100% compatibility. That said, we have a handful of users that have had no issues running it on 10.11. I’m not sure of the complexity of their sites, however.
Taken from our FAQ:
We’ve built RapidWeaver 8 so that it runs on 10.11, but this is unsupported, and due to the OS being fairly old you may encounter a few issues. We recommend you run RapidWeaver on the most up-to-date OS that you can.
https://www.realmacsoftware.com/support/rapidweaver-support/