Below is a short step-by-step tutorial on how to get private keys for OneDrive for Business.

1. Go to Microsoft Azure Portal using your OneDrive for Business admin or Office 365 account
   
2. Click on the Azure Active Directory
   
3. Open App Registration subsection
   
4. Add new registration by clicking the New Registration
   
5. Specify the application name like SqlBak, leaving the Supported account types settings with the default value (Accounts in this organizational directory only (net.net only – Single-tenant)). For the Redirect URL, you have to specify https://sqlbak.com/oauth2/onedrive4business/. Please leave the type of the application as Web. Once the settings are made click on the Register button.
   Note: Redirect URL must be specified exactly as in the blog post, including the trailing slash.
   
6. Copy Application (client) ID and Directory (tenant) ID and paste them into the appropriate fields in the destination settings at your backup job settings
   
7. Now go to the Certificates & secrets section and click on the New Client Secret button, specify any name and key expiration date. Then click on the Add button.
   
8. Copy the secret key and past it into the appropriate field in the destination settings at your SqlBak backup job settings