These structures are either from experiment (published in the literature) or from the IZA website.
If you want to minimize a zeolite or MOF structure, then you need a forcefield for it (and a good one).
So yes, options "FlexibleFramework and FrameworkDefinitions" need to be there and FrameworkDefinitions.def needs to contain a good force field for the framework.
If you want to minimize molecules inside the framework, the you can keep the framework fixed and "FlexibleFramework and FrameworkDefinitions" are not needed.
If you want to minimize a zeolite or MOF structure, then you need a forcefield for it (and a good one).
So yes, options "FlexibleFramework and FrameworkDefinitions" need to be there and FrameworkDefinitions.def needs to contain a good force field for the framework.
If you want to minimize molecules inside the framework, the you can keep the framework fixed and "FlexibleFramework and FrameworkDefinitions" are not needed.