It is part of the same universe with the same characters involved in the show. It also happens right after the events or at least it's suppose to happen right after. We won't know for sure until it is finally released.

It covers part of The Lost Tomb series with The Lost Tomb being first in the series. This season is set after Explore With the Note TLT2.

This show is actually the prequel to the Lost Tomb series. It's where the formation of the Nine Families that are mentioned in the series, even though some of the characters aren't exactly like those in the rest of the series.