If you don't have a subscription to Microsoft 365 Family or Personal, you can only add up to three files in your Personal Vault. If you do have a subscription, you can add as many files as you want (up to your storage limit).
Folder lock is not possible outside of vault. If you share any files or folder with anyone, it would be available only for that particular user.
The files on your OneDrive are private until you share them. Keep in mind that when you share folders with Edit permissions, people you share with can add the shared folders to their own OneDrive.
https://support.microsoft.com/office/8a63cd47-1526-4cd8-bd09-ee3f9bfc1504
To add a shared folder to OneDrive,
- Sign in to OneDrive on your browser with your Microsoft personal account -
https://onedrive.live.com/
- On the left navigation pane, under OneDrive, select Shared. Files and folders that you can add to your OneDrive are marked Can edit.
- Locate the folder you want to add, select the circle in the folder's tile, and then select Add shortcut to My files on the top menu. Or right-click a folder and select Add shortcut to My files
Share the files or folder to specific users,
- Pick the files or folders you want to share by selecting its circle icon.
a. If you're using List view, select the circle on the left side of the item. You can also pick multiple items to share them together.
b. If you're using Tiles view, select the circle in the top right corner of the item. You can also pick multiple items to share them together.
- Select Share icon at the top of the page
- Under Send Link, select Anyone with the link can edit to open the link settings.
- If you're using OneDrive for work or school, you can change the link permissions. Otherwise, skip this step
- Once you have set all your link settings and permissions, select Apply.
- In the Name, group or email field, start typing the email addresses or contact names of people you want to share with. When you begin to enter info in the box, you can also choose a contact from the list that appears.
- Include a message below the Name, group or email field, if you want and Send
https://support.microsoft.com/office/9fcc2f7d-de0c-4cec-93b0-a82024800c07
Hope this information would be useful to you. Please feel free to get back if you need any additional info.
Thank you!
Ravikumar
Help the next person who has this issue by indicating if this reply solved your problem. Click Yes or No below.