The 'mod' is for 1.14.4 (versions from 1.7.10 to 1.14.4 exist but current support is 1.12.2 to 1.14.4), which type are you after: Vanilla, Bukkit, Forge or Fabric? If for Forge/Fabric just download it, put it into the mods folder and it should work. For the Vanilla version of the mod just install it like Optifine, just double click it and it will do the rest. I don't know about the Bukkit version as it's not my area of expertise.
@lillebenni_ttv, If a Server is involved, it's a bit different. But Single-player, it works just fine for me with the most current Fabric, Fabric-API, and the latest BBOR. Questions? Problems? Ask away, we'll be glad to help where we can. And if you wish to use this on a Bukkit/ Spigot server, you either HAVE to be the server admin or you HAVE to be good, trusting friends to have this uploaded to the server for this to work. But let's see you get the single player/ client side happy first.
I'm a bit confused. "Elaborate" on what? And no, this would not work on Realms, even if it is YOUR Realm and you uploaded it. The server simply HAS to have the proper plugin, and Realms doesn't deal with plugins at all. The best you can do is run a local copy with the same seed.
I'm using a Multiverse server, so I have more than one Overworld, more than one End, more than one Nether. The Origional Overworld and Nether behave just fine. The additional Overworld and Nether appear totally out-of-wack in locating structures. I suspect Multiverse throws BBOR a curve-ball.