The content delivery networks (CDNs) used by AstalaVR often use temporary tokens. This means you should download the file immediately after the link is detected rather than saving the link for later.
AstalaVR site support (NSFW) · Issue #13332 · yt-dlp ... - GitHub astalavr downloader
VR content requires high bitrates and resolutions (4K/5K) to look clear in a headset. The content delivery networks (CDNs) used by AstalaVR