On Java Edition the wind burst will take effect upon the hit of any entity no matter the players movement conditions that I have tested, although in the most recent Bedrock preview the same level three enchantment only takes effect on an entity if the player were to "crit" the entity thus they must be falling to activate it. This means that on java you can combine a jump and wind burst to achieve heights of around 10 blocks, on bedrock the highest I could achieve in testing was a unimpressive 5 with an unlucky 1.5 when I attacked at max downward velocity from a simple jump. this completely hinders the effectiveness of the enchantment and takes away the reward and desire to obtain this enchantment. (all tests were done with the wind burst III enchantment)