I have a NAS device at home that has other data on it. I would like to create a folder on the NAS and use it to store backups. If I do this and initialize the storage will my other data on that disk be affected?
Nope, your existing data will be fine. So long as you point the Duplicacy storage at that newly created folder, it’ll only write data there and won’t delete anything apart from deleting its own chunks in that folder structure when it comes to pruning.