To backup to OneDrive, you need to add permissions to the folder you are backing up to.
1. Find SQL service account
- Open Windows Services app
- Find SQL Service
- Go to properties
- Go to Log On tab
- Copy account name
2. Add permissions to folder
- Right click on OneDrive folder and choose properties
- Go to Security tab
- Click Advanced button
- Click Add
- Click Select a principle
- Paste account name in check name field
- Click OK
- Tick Full control option
- Click OK