Ensure LTspice Simulator is downloaded onto this computer.
LTspice Simulator can be downloaded for free at: https://www.analog.com/en/design-center/design-tools-and-calculators/ltspice-simulator.html
Make sure to sync LTspice to latest release ("Tools" menu, "Sync Release").

Double-click the .asc file to automatically open it in LTspice Simulator. For more details, please read the simulation guide found in this zip file.

For support, you can post your questions in the LTspice forum in ADI EngineerZone: https://ez.analog.com/design-tools-and-calculators/ltspice/
You will need to create an account and log in to post questions.