To run iMacros 9.0.3 , you must use Firefox 56.0.2 (the last pre-Quantum version). Not Firefox 9. Otherwise, the APIs won't match.
The most reliable source for is the Internet Archive’s software collection. Directly searching for "iMacros-9.0.3-fx.xpi" is risky; instead, use this protocol: imacros for firefox 9.0.3 download
: Using outdated extensions and browsers exposes your system to vulnerabilities. 💡 Modern Alternatives To run iMacros 9
To get your automation environment up and running, follow these steps: To run iMacros 9.0.3