。
I'll come by to pick it up tomorrow.
Literal
Tomorrow that [object-を] humbly-receive [purpose-に] humbly-visit.
Layered keigo. いただく is the humble form of もらう ('to receive'), いただきに is the humble-verb-stem + purpose に. 上がる here is its humble sense 19 ('to visit') — the old Japanese metaphor of 'rising' to enter someone's home, because it's polite to frame entering a superior's space as ascending. Together: 'I will humbly come to humbly receive that.' Extremely deferential — business or service context.