Changing drive format for OneDrive?
This extract from the Office Support Page from Microsoft lays it all out:

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• File systems: NTFS or HFS+ (case insensitive)

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See this page from 2011 on StackExchange which recommends a paid app iPartition that will apparently change from case sensitive to case insensitive.

Disclaimer: I have no financial or other interest in Coriolis Systems Ltd., developers of iPartition 3.