A Deinotherium only deals with survivors of level 85 or higher, and only takes a Beer Jar, which has to be in your last hotbar slot. Kill the rest of its pack first, then walk up slowly and read its face. Head shaking, relaxed ears and a lowered trunk each raise the chance it accepts the next offer. If it rolls its trunk up or flattens its ears against its head it will refuse, so back off until it stops watching you and approach again: retreating costs you nothing, pushing through a refusal makes it hostile.