Description of problem: Hi im trying to make a project with friends but I do not want random people joining in, i dont find any setting in the group preferences to make it invite only
Just noting you cannot stop people from joining a collection project, but as @thomaseverest said you can control whose observations appear in the project via the Users requirement.
This would be a nice feature; like if checking the box under “Project Members Only” generated a private link for joining the project. I’ve had a couple cases where I wanted to limit participation to a specific group of people, but I wanted inclusion to be voluntary within that group.