Creating teams and GIS App for Professionals questions

I want to know more about Creating a Team in Gaia.
The only information that I can find on the Gaia web site says the following:

Replace manual processes and legacy GPS devices, with the best GIS app for collecting data out in the wild.

Outdoor GIS for search and rescue, wildland firefighting, government, land managers, oil & gas, farming, and other industries.

Gaia GPS for Teams costs $40/user/year, for a limited time.
Start 30-Day Trial

Please tell me more. Here are some questions that I have.
1. What more do I get is I upgrade to the GIS App for Professionals?
2. Is it a whole different app?
3. Does people that I add to my group also have to pay $40 to use it?