None of the Voice Actors from Hotel Transylvania (2012) and it's sequels reprised their roles in the TV Spinoff.
Mavis is 114 years old on this series. Her father's sister is there to run the hotel while he is traveling.
The show takes place before the events seen in Hotel Transylvania (2012) and Hotel Transylvania 2 (2015) because Mavis has yet to meet Johnny and has yet to have her baby.
This takes place while Mavis was in her early 100's, a.k.a her teen years.
The director of the show Robin Budd is also the director of Ruby Gloom (2006). Both shows have a horror setting to them.