Xcode error: "Build failed because SwiftyDropbox.swiftmodule is not built for arm64" (SDK v.10)

To be honest, I'm not familiar with the mentioned package. I cannot imagine any package, targeting particular platform, to expect exclusion of the same platform though. 🤷 (including arm64, but not only)

PS: Probably you are trying to do something like cross-compilation with pre-build package. Clarify to yourself what you're going to do and everything's gona be fine (I believe). In any way all packages have to be the same architecture for one executable binary though (not some mixture as seems to be in your case). If you plan mixed architecture project, split the different archs in different binaries, for example.