The oldest version this software is compatible with refers to Windows Vista. There is no information on the official website related to Windows 2000 or version from that period when it was launched. The recommended system specs state that EasyACCT Professional requires Windows 8, Windows 8.1, Windows Vista, or Windows 7 to work correctly and stable. You can find details about it on the official website. The product(version) you are looking for might be discontinued. Contact the developer to find about it.
Note: Contact button is on the bottom page where the developer name is located.