This is related to the spaces in your path definition. Please try the following Batch CMD command script.
REM adapt the following to the actual path of FHBatch.exe
set FHBATCH="C:\Program Files (x86)\FlowHeater V3\BIN\FlowHeater.exe"
%FHBATCH% "C:\Users\bgreenway\Google Drive\Product Data\Excel-to-Multi-Brand.fhd"
if %ERRORLEVEL% LSS 0 goto error
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