This one is again a bit of housekeeping in terms of catching up with build topics from back in November, and to be honest I don't think it requires a separate post, but for ease of review and searching I'm writing one.
The rear ARB requires a connection from the bar to the wheel hub, this is achieved through the use of drop links. This is a common design for most cars although you typically find the connection goes to a rear wishbone.
Caterham supply a drop link and bracket for either side of the car. The bracket was referenced during the wheel speed sensor install, https://www.caterham7diaries.com/420r/speed-sensor-sender
The bracket is fastened to the rear of each ear using the forward most bolts, and the lowermost bolt hole on the bracket is used to connect the drop link.
Out of the box each drop link has it's connecting or supporting bolt in the same direction, due to the positioning of the ARB bracket such a configuration is not compatible. You need to slacken the locking nuts, resize the drop link to suit and turn the connecting bolts so they are opposing each other via 180 degrees. Once complete the drop link can be connected the bolt hole on the rear of the bracket and into the hole on the bar. You do need to reduce the size quite a bit. There is a selection of holes to use on the bar, I used the second one to the left as you look at the bar. I may change this to the second to the right, as per the assembly guide.
That really is it, very straightforward, I appreciate this is rather short, if you do think there is anything else I could add then please let me know.