As OFF is in capitals it looks to be an acronym (possibly pronounced 'oh eff eff' rather than 'off'), searching the web for OFF as an acronym I found two which relate to Object Oriented Programming (or OOP).
The first one is
Object File Format: Object files participate in both program linking and program execution. For convenience and efficiency, the object file format provides parallel views of a file's contents
The second one is
Object File Factory: an object for creating other objects – formally a factory is a function or method that returns objects of a varying prototype or class from some method call, which is assumed to be "new".[a] More broadly, a subroutine that returns a "new" object may be referred to as a "factory", as in factory method or factory function. This is a basic concept in OOP, and forms the basis for a number of related software design patterns
They could be using either meaning of the acronym, neither expansion really fits into the sentence but the second makes a little more sense giving
We want this product built Object File Factory of XXX platform
If this meaning is, indeed, what the writer intended it would have been better written as
We want this product built using the Object File Factories of the XXX platform
My suspicion is that this is what was intended but they got someone with little or no knowledge of OOP (and possibly an imperfect knowledge of English) to write up the job specification so the spec got a bit mangled. I think it would be quite reasonable to ask them if they were using OFF in this sense, even if they are using an OFF acronym I haven't managed to find you will still look as though you know what you're doing!