There are 2 recommended options for voice chat while playing.
The easiest option is to choose one of the Camp Cardboard audio channels that were created for real time play. There are currently 4:
A - Dining Hall
B - Rec Hall
C - Clubhouse
D - The Deck
They are all the same, having multiple different channels just allows for multiple real time groups at one time.
Google offers free video conferencing that works very well. I recommend turning off video, it uses less bandwidth and should be more stable.