When we moved in the military, the mover said to use either -
plain charcoal in old pantyhose so you could wind it around on the shelves and contain it.
or
dried used coffee - said after making morning coffee, pour grounds onto paper towels to dry, then place this into used panty hose or something else that is porous, but so it will not have grounds all over the freezer.
either one of those plus crumbled newspaper to help absorb moisture.
When we got the freezer delivered 2 months later, no mold. We used the plain charcoal, then used it later - out of the pantyhose - to make burgers.