A Microsoft file hosting and synchronization service.
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I want to help you, but tag "office-onedrive-client-itpro" focuses more on general issue of OneDrive, including deployment, installation, and troubleshooting like file synchronization.
According to following screenshot taken from "Set the default storage space for OneDrive users", I would like to sugget you contact Microsoft support to confirm it.

Besides, in my opinion, I do not think "4 x M365 E3 and 1 x Onedrive Plan 1" meet the conditions to increase storage, as OneDrive for Business (Plan 1) has 1 TB per user instead of unlimited individual cloud storage. So OneDrive for Business (Plan 1) is not one of the qualifying plans as the image says.

For more details, please refer to "Compare OneDrive cloud storage pricing and plans", the screenshot above is taken from it.
Hope the information could be helfpul.
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