I have read, some years ago, that this joint, between the shower pan and the walls, should not be caulked, because caulking this junction will close off the space behind the shower enclosure so it cannot breathe, and moisture will then allow mold.
Considering how loosely my rig is put together, this seems unlikely.
Mine came from the factory caulked.
Buck: 2004 Wilderness Yukon 8275S, now memories.
Star: Open range LF297RLS. 2 air conditioners!
Togo: 2014 Winnebago View Profile, 2013 Sprinter chassis; 16 mpg
Snow: 2020 F250 diesel
AD5GR