What do you mean by that?
A workflow similar to typical cloud services is not really possible. (Example google docs, where you can work in parallel on the same document.)
Multiple users can always work on one project as long as you manage who does what when. (No software support needed.) And as long as you can share files.
I would suggest any version control system to help there. (I prefer git but you can use any system you want.)
The limitation of course is that you can not work at the same time on the same files. (Merging kicad files is not really a good idea.)
For the schematic i would suggest you break down your project into multiple stand alone modules. Fix the "interface" first and then everyone can work on their respective module. (each module is a hierarchical sub circuit.) Because a hierarchical sheet is a separate file, everyone works on their respective files. No merging required.
The pcb design might be a bit harder to do by multiple people.
There is no module support in pcb_new.
Maybe it would be better to break down your project into multiple pcb's that are assembled later on? In other words: Stack multiple pcbs on top of each other, each pcb with its own responsibility.
Something like this (Image found via a google search for pcb stack)
This has the benefit that if something goes wrong in one module you only need to change that module.