It looks like there's a licensed version of Delphi that can be used by the community to help build the platform again. Delphi Community Edition 10.3 should let developers build the current platform from source. The current platform is built with Delphi Professional 10.2.
You can get it from here after registering: https://www.embarcadero.com/products/delphi/starter
Please let us know how it works for you.