Permission for drive
When Macs were first able to run Windows 7 (SP1), the Boot Camp Support Software installed the software necessary to allow reading of Mac OS Extended (Journaled) volumes from Windows. Also, OS X (macOS) could read from Windows NTFS volumes.  Neither Apple nor Microsoft provided a way to allow writing to the other operating system's volumes.


  Unfortunately, as Apple has progresses toward the new APFS format, some (if not all) Windows Boot Camp installations have loss the ability to read from macOS volumes. 


A possible solution would be to purchase a third party product such as the Mac ToolBox from Paragon Software. 

Another possible solution would be to create another separate FAT32 or ExFAT formatted drive. You could  then use the drive for storage of files used by both operating systems or to transfer files between operating systems.

Finally, if you have a high speed internet connection, then you could copy small files to your iCloud drive and access the files from both macOS and Windows.