"Payola, in the music industry, is the illegal practice of payment or other inducement by record companies for the broadcast of recordings on commercial radio in which the song is presented as being part of the normal day's broadcast."
Simply put: SubmitHub in no way guarantees that record companies will have their music broadcasted. It is simply a guarantee that the recipient has given the song due consideration -- in fact, more than 80% of submissions on SubmitHub are "declined" for coverage even though they've used premium credits. The data clearly shows that the small monetary component does not influence likelihood of being broadcast; it simply ensures consideration.
For more detail, see this article: https://www.submithub.com/help/HPXiC8GTaxbEWzJqc