It seems they hide it rather than clarifying, but you can find it in web-archive :
Motion recognition based on Seeed XIAO BLE Sense - Hackster.io (archive.org)
or you can find the revised version that they added this can only work in very old version 1.0.0 but still the training code and model are wrong :
Motion Recognition based on Edge Impulse - Seeed Wiki (seeedstudio.com)