prepositions - in order to [gerund] or [infinitive]?

There are few questions and answer on the choice of gerund versus infinitive.
From what I understand, when conveying a purpose the infinitive should be used:

I use my key in order to open the door. [correct]
I use my key in order to opening the door. [incorrect]
I use words to describe my dream. [correct]
I use words to describing my dream. [incorrect]

Yet I read the instruction on an English lesson book:

"Use similes to describing the animals here below."

Could you please confirm what should follow "(in order) to": the gerund or the infinitive?

Answer

That's a mistake. It should be Use similes to describe the animals here below. You might want to get a different book.