The Fandom Post is reporting that the plans have fallen through and the upcoming digital debut for the Shaman King manga will not be happening as originally reported. The delay has also impacted the digital release for Shaman King Zero, Shaman King: Flowers, Shaman King: Super Star, and Shaman King: Red Crimson, all of which are now paused since they wanted to have everything out for fans as close as possible.
No new dates are set for the main series and spin-offs yet but the company intends to update as soon as possible on it. This delay does not impact the physical print releases that are scheduled for 2021 and 2022.
When released, the manga will be available digitally through Kindle as well as Amazon Prime and Kindle Unlimited.
Source: The Fandom Post