Saving the project structure works well enough, as long as team members compartmentalise their work and avoid convoluted overlapping changes. I would recommend developing new features on separate prototyping layouts/sheets, and only do a proper "manual" merge if necessary when everything is in place.
Also, I would strongly suggest to use an actual versioning system, e.g. Bit Bucket + Smart Git, or any other good alternative you are familiar with. Just make sure you set it up to ignore all "ui" and backup files, otherwise these will "pollute" the history log when searching for diffs