Before diving into the download and installation, let’s clarify the terminology. "RG Maker" is often used interchangeably with (specifically RPG Maker VX Ace or RPG Maker MV, depending on the version numbering). Version 20.0 likely corresponds to an updated release or a translated build of RPG Maker MV (which is version 1.6+ but localized as 20.0 in some regions).
Run a quick test:
If you are trying to install RPG Maker games on an (like the RG351): Emulator : Use the EasyRPG core in RetroArch. rg maker versao 20 0 download install