Hi @Rajan Radhe
If you are looking to access other users drive in your tenant using Microsoft Graph API, you can use this GET https://graph.microsoft.com/v1.0/users/{user-id}/drive
Graph API endpoint.
If you are using **client_credentials flow **you need these Permissions (from least to most privileged) Files.Read.All, Files.ReadWrite.All, Sites.Read.All, Sites.ReadWrite.All.
If you are using Authorization_code(delegated Permission), users OneDrive is needed to be shared with you which can be done by Global Admin (Admin Center->Active Users->User->OneDrive->Get access to file) or User can share his drive from Site Collection Administrators as shown below screenshot:
Please provide the required permission and use the Graph API.
Hope this helps.
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