Soundiiz is supporting the 1001Tracklists playlists to other streaming services with the URL link you can found directly in the browser address bar.
For that, simply go to your playlist on 1001Tracklists and copy the URL you can found in the browser navigation address bar.
The URL should like for example: https://www.1001tracklists.com/tracklist/2hcv1nc1/paul-van-dyk-chris-element-vonyc-sessions-679-2019-11-05.html
Then simply go back to Soundiiz, tab Playlists and use "Import playlist" button in top right of the interface and select "By URL". Then paste your URL and follow steps !