ASF stands for Advanced Systems Format and is a proprietary digital video and audio container format. The ASF format defines how the data in the file is organized but does not define the encoding method. WMA (Windows Media Audio) or WMV (Windows Media Video) are often stored in the ASF container.

But you can open ASF files on Mac with Elmedia Player. It is the easiest and most reliable solution that delivers impressive and smooth video playback.

Elmedia Player is the best ASF player Mac users can rely on. This media player for Mac provides enhanced versatility and can open almost any file format, including MP4, ASF, MOV, AVI, MKV, MP3, WMV, and WMA. It even plays niche formats like FLV and SWF.

You can read this article https://www.elmedia-video-player.com/asf-player-mac.html and maybe it will help you