OneDrive End Of Support Notice for Vista SP 2, Windows Server 2008 and Mac OS X 10.9

The OneDrive engineering team is committed to bringing you the best, most secure, end user experience possible. To support that commitment, the OneDrive Desktop application (sync client) is updating the matrix of supported operating systems to align with Office 365 and Windows support. These changes will go into effect November 1st, 2017.

NOTE: These operating systems have been out of mainline support for several years now

After November 1st, OneDrive will be phasing out support for the following operating system versions:
Windows Vista SP2 (All versions)
Windows Server 2008
Mac OS X 10.9

Here's what will happen:
Existing OneDrive sync client installations on unsupported operating systems will stop updating. These clients will continue to run, but functionality will no longer be tested. It is not advised to continue to run on these unsupported operating systems.
New installations on unsupported operating systems will be blocked.
Bugs and issues found on or specific to unsupported operating systems will no longer be investigated or fixed.
More here: OneDrive End Of Support Notice for Vista SP 2, Windows Server 2008 and Mac OS X 10.9 - Microsoft Tech Community