Dual Boot Windows and Mac: Will I be able to share one HDD for files from both OSs?

I currently have Windows 10 on an SSD and have a 2 TB HDD for storage. I want to buy another SSD for just OSX. If I want to save something to the HDD while I have OSX booted up, will I be able to or will there be conflict becasue there are files saved there from windows 10? Will I have to partition?