I believe their application is a scam to get free essays to give to their clients and that they don't have enough work to take on new writers.
I have an Oxbridge 1st (bachelors and masters) plus an MBA from a top business school. Native English speaker, A* in A-level English plus significant former copywriting experience.
Their application required a rather time-consuming 1200-word from scratch essay with a minimum of 10 references, plus I submitted an additional piece of previous work that had been independently marked A+ by a top international university.
Rejected on the spurious grounds that one reference used was "too old", despite the fact that no such criteria were stated. The reference referred to the original paper presenting a synthetic route that is still in use today, so is entirely valid to use.
Writers, do NOT waste your time applying here. You will spend many hours and then they will take your work and reject you on some arbitrary criteria that was not even defined beforehand in the requirements. There are many other companies with more work that do not scam both writers and clients.