Thread:Extension talk:ArticleFeedback/Fatal error: Call to undefined method OutputPage::addModules() in /var/lib/mediawiki/extensions/ClickTracking/ClickTracking.hooks.php on line 73/reply

The various methods with "module" in their name (i.e. OutputPage::addModules, OutputPage::addModuleStyles, OutputPage::addModuleScripts, etc.) were introduced with ResourceLoader, so they most certainly aren't present in 1.15.

I'd suggest upgrading your wiki to 1.18 (which hasn't yet been officially released, but the branch should be stable enough, I think) and then trying again, although it might be that ClickTracking is compatible only with the latest trunk, but I hope that's not the case.