How to connect toroidal transformer from wall power
The wiring was correct as follows:

Mains:


Brown (hot) to one primary blue
Blue (neutral) to one primary blue


Secondaries:


Red going into AC input of rectifier bridge A
Black going into AC of rectifier bridge A
Orange going into AC of rectifier bridge B
Yellow going into AC of rectifier bridge B


Output voltage of secondaries: 15VAC

Bridging output of both rectifier bridges with a 2.2uF cap.

Output of combined secondaries from both rectifier bridges: 48VAC

The problem was that I was not using the multimeter properly.