To connect to Excel we use the Microsoft Office Drivers on a 32 bit system this is JET for XLS files and ACE for XLSX files. On a 64 bit system JET is unavailable so we use ACE.
If you do not have the Microsoft Access Runtime installed you can download the runtime from here.
However note that if you already have 32 bit office installed you cannot install the 64 bit runtime. In this scenario you have two options
Uninstall Data Sync 64 bit and install the 32 Bit edition instead this allows Data Sync to access the 32 bit components on your system.
Uninstall 32 Bit Office and Install 64 Bit office instead.
If your running Data Sync on a server the recommended configuration is to keep all components 64 bit therefore you should run the 64 bit version of the Microsoft Office runtime.