You cannot download ASDM as a traditional installer from a third-party site; it must be retrieved directly from your firewall or the official Cisco portal. Navigate to https:// in a browser.
Users report that version 7.18(1.152) can take several minutes to "Check launcher version compatibility". Fix: Upgrade to ASDM 7.18(1.160) and Launcher 1.9(7) for significantly faster login times. cisco asdm 7.18 download