A Microsoft file hosting and synchronization service.
Hi bing_247,
~~Thanks for posting back and providing the detailed information.~~
According to your reply, you must have used the "Anyone" link to share the folder with others before. To reconfirm it, you can go to OneDrive for Web, try the same steps as shown in the gif below, and check if you can find these 10 persons. If so, to share the file, you must also use the Anyone link as well (select the file you want to share, click Share, select the "Anyone" link, then click Copy and paste the link into the email). After that, they should be able to open the file.
~~We look forward to your response. Thanks for your cooperation.~~
Sincerely,
George | Microsoft Community Moderator