Unofficial downloads are a primary source of trojans and ransomware for macOS.
Apple offers a 90-day free trial of the entire video editing suite, which includes Final Cut Pro, Motion, and Compressor. You can download this trial directly from the Apple Final Cut Pro Trial page . Motion 5.5.3 Free Download
If you are looking for a legal way to use the software, you have the following options: Unofficial downloads are a primary source of trojans