I have got a user with a read NTFS permission and modify Share permission. Why he is unable to modify the shared folder?

It is because your user gets the less amount of permissions after a combinaison between NTFS and Share permissions. So, your user only have the right to read the content of your share folder. If you want to solve this problem, give the modify NTFS permission for this user. Please remember to click “Mark as Answer” on the post that helps you, and to click “Unmark as Answer” if a marked post does not actually answer your question. This can be beneficial to other community members reading the thread. Best regards.

You're right. Thanks you