And I checked the wikipedia page "list of asset management firms", there is also the top 10 in the world close to the one you sent, however they do not manage billions but TRILLIONS. BlackRock: AUM 6.3 trillion, Vanguard 5.1 trillion, UBS 3.2 trillion, JPM 2.8 trillion, Fidelity 2.1 trillion. What is the source of your chart? I dont know how Woodbrook can be in the top 5 in Europe with only a couple of billions of AUM...
And even if they reach 20 bn of AUM they will still be far from the top 5 in Europe, check any of the European companies listed there and they have many more AUM...
Then when looking at their revenues, I tried to find a comparable company. Tilney manages 24 bn GBP (2017) of AUM, and had revenue of 226 mill GBP.
I found similar figures for other companies, so if Woodbrook manages at least 2 bn $ then revenue should be a few tens of millions, and could easily reach 100 millions if they reach 20bn AUM.