When I went to upload a IG based dimensioned video you will get a surprise warning and failure if it’s not
900×1600 pixels. 620 x 1200 is not going to work like it would for IG.
I kept seeing “The file has the wrong ratio. Your video must have a 9:16 aspect ratio”.
This is fixed by changing the image size in photoshop and then when you export from the timeline it will give you the correct video size to add to the Spotify artist manager.
For more info on this article I used to fix my issue please read source article