Sidify Spotify Downloader Crashes

I recently tried converting a song from Spotify with Sidify, but after tracks are loaded into it, pressing the "Convert" button causes it to crash.
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Edit: I found a working version on another website (Nmac) that was uploaded this week.

The trouble to me is about how to get a best Spotify downloader to download Spotify and play offline on any devices without limitation. We know all Spotify free users can enjoy online, no right to download and play offline. But now, we can use a tool to help us, it is named Tuneskit Spotify Music Converter, you can use it to remove DRM from Spotify and convert to MP3, M4A, M4B, AAC, WAV, FLAC, etc at 30x speed without hampering the quality.