Download standalone version
Download it here: Rasterbator Standalone 1.21 (887kB)
Please note that the standalone application is several years old and there are no plans to update it. The rasterbation engine is less accurate and has less features such as output modes. On the other hand, it has no size limits.
Download the zip file, extract the entire archive and run. If you get errors, you probably need to install the pretty ancient .NET framework 1.1.