Strictly speaking I think that in an IT context 'applicatief' should be interpreted as 'relating to the application' (i.e. application software as opposed to operating system software). That would mean, however, that here the source text should have read 'intern*e*, applicatieve beveiligingsparameters', which in my view would translate to 'internal, applicative security parameters'. Since the source text reads 'intern' (without the 'e' at the end and without a comma, I tend to agree with Textpertise and would opt for 'internally applicable security parameters'. Further context would then be required to clarify whether 'internally' relates to the software or to the organisation.