Registered App > Grant Permission to OneDrive?

Hey! From what you’ve described, it definitely looks like the issue is caused by the lack of a OneDrive license. With the Power Automate Free license, unfortunately, you don’t have access to OneDrive for Business, which is required for the API and everything you’re trying to do. Yes, the Office 365 E3 license includes OneDrive for Business and would solve the problem. Without this (or an equivalent license), the user cannot access or create their personal OneDrive site. The PowerShell command to force OneDrive provisioning (Request-SPOPersonalSite) only works if the user has a valid license. Without it, it won’t run at all. I’d suggest temporarily assigning the Office 365 E3 license to the user you’re testing with, just to see if that fixes the issue. Once the license is active, log in manually to https://portal.office.com/onedrive to trigger the initial OneDrive setup. After confirming that it works, you can decide on the most suitable solution.

Alternatively, you could use the OneDrive for Business Plan 1 license, which is cheaper and only gives you OneDrive (1 TB of storage) without the other Office apps