If you are getting notifications from AlphaExplorer, then your Mac is infected with adware. AlphaExplorer is adware for Mac.
AlphaExplorer changes setting in your Mac. First, AlphaExplorer installs a browser extension in your browser. Then, after AlphaExplorer hijacks your browser, it modifies settings in the browser. For example, it changes the default home page, modifies search results, and displays unwanted pop-ups in your browser.