Personal Vault is a protected folder in OneDrive that can only be accessed through additional identity verification. It provides extra protection to your most important files. Learn more at the OneDrive help center: https://support.microsoft.com/onedrive

Personal Vault works on your desktop, in the browser, and on a mobile device. Here's how to set it up on your mobile device:
1. Download and install Microsoft OneDrive from the Google Play Store or the App Store.

2. Open the OneDrive mobile app on your Android or iOS device, and sign in with your Microsoft account.

3. Select Personal Vault under the Files tab.

4. Select Continue.

5. Verify your identity by entering your password. Then use text or email to get a verification code and enter it.

6. Create a 6 digit PIN code and confirm it. If your mobile device has face recognition or a fingerprint reader, you will have the option to use that to unlock your Personal Vault.

Support article: https://support.microsoft.com/en-us/office/video-how-to-use-personal-vault-10dbc72a-a3c4-4b8d-86bf-c7493f3866b0?ui=en-us&rs=en-us&ad=us