Build DPH from source.

Extract the entire source ZIP

Choose a writable local folder. Extract all files and keep the folders together; do not open or build files while they are still inside the ZIP.

Install the language design package

Before opening the project, start RAD Studio 37 and choose Component → Install Packages → Add. Inside the extracted folder, select export\DAT-component-kit\DelphiProjectHandoff\DesignPackages\Win32\Release\DATLanguageManagerFMXDesign.bpl.

Leave DATLanguageManagerCoreRuntime.bpl and DATLanguageManagerFMXRuntime.bpl in that same folder. You do not add those two BPLs separately. Confirm the design package is enabled; restart the IDE if prompted. The Win32 design package is correct even when building the Win64 app.

Open the project in the IDE

In RAD Studio, choose File → Open Project. Browse to the top level of the extracted source folder and select DelphiProjectHandoff.dproj. Do not open DPH.UI.Main.fmx by itself. Its two language controls are already on the form.

Build the Windows edition you need

In Project Manager, select Win32 or Win64, select Release, then choose Build. The project already includes the translation dependency in its compiler search path; there is no separate dependency-preparation step.

Run your build

Open bin\Win32\Release\DelphiProjectHandoff.exe or bin\Win64\Release\DelphiProjectHandoff.exe inside the extracted folder. Check that WebView2Loader.dll is beside the executable. Keep the source folder's Localization, migrations, help, and images and icons folders in place. Formatted embedded pages also require Microsoft WebView2 Runtime.