The .rar archive may contain the Thin Client, the Full Technological Platform, or the Training Version (e.g., training_8_3_21_1709.rar ).
You can find official downloads and documentation on the 1C:Enterprise platform page or the 1C Online Catalog . 8.3.21.1709_windows.rar
Use a utility like WinRAR or 7-Zip to extract the contents of the .rar archive. the Full Technological Platform