Online courses do not offer you observed teaching practice an feedback, and so even the very best ones aren't really worth doing. Anybody can read and write about teaching theory, or learn what minimal English grammar a TEFL course covers, but the actual experience and feedback you gain from experienced teachers in classroom situations is invaluable to a new teacher who is serious about doing a good job for their students.

I realise location and time may be an issue, but you would do better finding a classroom based course as close to you as you can get and consider attending a weekend and evening course over the course of a few weeks.

I've never heard about the online provider you mentioned, but knowing where in the world you are based would help as I could then advise you better.