I also tried to get information about Ultius. My research shows that they are not based in the US as they claim. Still, being a non-English writer, I sent them my cover letter and resume, but I was ignored. Below is a sample of my credentials as an academic writer, maybe someone will be interested.
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Cover Letter - Academic Researcher and Editor

I am a freelance academic writer/ editor with over 4 years' experience, similar to what the above posting requires.
I am an ardent researcher, with the proven ability to deliver excellently researched, well-written and appropriately referenced academic papers with ease. Mine is an excellent standard of Written English. I am especially proficient with the British and American English variants. Further, I am keen to adhere to instructions to the letter, and my turnaround time is unrivaled. I have never missed a deadline, no matter how critical it was.
My schedule typically allows for up to 15 hours of freelance work daily, within which I can handle as much as 30 pages of work. I would be delighted if my time and skills would be put to good use by your esteemed agency.
While I pride myself for being an all-rounded writer, able to handle even the most complex of tasks, I particularly excel in the following specialties: Social sciences, business, nursing, healthcare, humanities, English, Literature, Engineering, and environmental sciences.I can also write at any academic level, from high school, to bachelor's, to Masters, and even PhD.
I have unlimited access to several academic journals and scientific databases, ranging from Ebscohost, to ProQuest, to Emerald E-Journals, to JSTOR, to Keynote, to Oxford Journals, to Palgrave Macmillan, to SAGE, and Springer, to mention but a few. I also have high speed internet access, and I am perpetually online. Kindly consider my application for the position.
I have attached the sample essay, my resume, and two samples of my work in MLA and APA citation styles, as requested on your website. I look forward to a positive response.
Yours Sincerely,
Essay Editor