Thanks Usel for these instructions - just fitted on in my electric seat. The only difference I found was for the gold screw. The screw was partially obscured by the seat base - I think if the front of the seat base was tilted up prior to removing it from the car it would’ve been easier to get to.
If anyone wants a non isofix bar you can have mine for free - just pay the postage!
You're correct, the seat base wants to be in its highest position. I do this before removing a seat, regardless of being electric or manual, because it makes getting to the bolts and the connector underneath easier.