Depending on the plugin, it might already have sensible paths to the Dalamud library folder. The [SamplePlugin](https://github.com/goatcorp/SamplePlugin/blob/master/SamplePlugin/SamplePlugin.csproj#L33) is an example of this. If it doesn't, or you don't use XIVQuickLauncher/XIV.Core then you need to manually edit the path. Tweak the `<DalamudLibPath>` folder to the location where your `Dalamud.dll` and files sit, and you'll know when you're successful when .NET stops screaming.
If for some reason your build of Dalamud is not a developer-enabled one, check the [Dalamud release server](https://kamori.goats.dev/Dalamud/Release/VersionInfo?track=) for a download URL.
Remember that when entering the dev plugin path in the Dalamud settings, to prepend it with `Z:` and take care of your slashes so they make sense under Wine.