For a service that skews older and domestic only (US), mobile app downloads will not represent the vast majority of downloads. International is where everyone watches these products on their phones, not in the US.
To be the #1 video on demand release at the same time as also having the movie released in theaters had to be a relief for WB. The fact the movie also made $16.7M in those theaters (almost double any other movie's true 3 day weekend open in the pandemic while only having 39% of domestic theaters open) would make them even happier - and thus, the fast tracking of Wonder Woman 3.
If anything, Disney might be a little upset Soul was not the #1 video on demand release for the year...and from the article, possibly not #2, either...although, that's probably b/c of the competition from Wonder Woman...if it had its own opening weekend, it probably would have grabbed the #2 slot...