Nevermind, I found the solution by dissecting what was done in this discussion:
I simply needed to specify the resource property:
href = Neos.Fusion:ResourceUri {
resource = ${node.properties.caseStudyPdf.resource}
}
Whereas before I was attempting this:
href = Neos.Fusion:ResourceUri {
resource = ${node.properties.caseStudyPdf}
}