How can I handle group projects?
Generally speaking, a poor way to handle such situations is to divide up the work to individuals and then try to assemble the whole at the end. 

If the group is reasonably small (say five or less) try to have regular meetings to brainstorm and outline things for the report. One person (probably the one with the best language skills) takes on the task of editor, or even writer. 

Pass drafts around frequently and update them based on feedback. 

If the group is larger, then do some division of responsibility, but to sub-groups, not individuals. Have each subgroup work as suggested above (brainstorming...editing...markups). But then, one or two people take on the task of getting everything together. Those two people need to monitor and shepherd the task throughout, making sure that the subgroups are doing their work productively. 

It might even be advisable in a long project, to shuffle the groups a bit periodically. Not a radical reshuffle, but just some cross pollination. 

You should also expect, and plan for, the fact that not every member will be able to contribute as much as others, or even at all, for various reasons, both legitimate and not. But just as important, don't set it up so that everyone needs to contribute in the same way. Try to draw on individual skills. Some doing research, some writing, some editing, etc. 

A team should be a team, not a herd of individuals. 

This might be different in a different field, but for an MBA it feels about right.