Hi!
The use of RStudio Cloud will meet your needs perfectly. You'll avoid all of the setup friction that you mentioned, and your colleagues will be able to dive in immediately. As well, RStudio Cloud makes it easy for you to share files, such as your R Markdown and data files, within the cloud environment--further reducing the friction.
I can't confirm, but I think the free version should meet your needs. Your colleagues will have to create their own accounts, and then when you share your space or project with them, they will need to save it to their own space.
Good luck!
Martin