In this sentence, "make it down" means "walk". However, walking is easy, but "make it down" means that it is very hard to walk down the driveway without falling. "Make it down" also has another meaning. "I hope you can make it down to my birthday party." Here, "make it down" means "come", and it doesn't mean that it is hard to come.

The key phrase here is 'make it'. The phrasal verb 'make it' means to succeed in doing something, or getting somewhere, in spite of difficulties. For example, you might say 'I can't make it to the party tomorrow. I have too much work to do' or 'I can't make it to the meeting before 7.30 am. The traffic is too heavy at that time in the morning.' The word 'down' is simply a direction. 'Make it' can go with any directional adverb. If you go from the house to the gate, for example, you are going down the driveway. So, "Succeed in going down the driveway in spite of the icy conditions" = 'make it' + down the driveway. In other situations, you could say make it through/make it up/make it out/make it over/ somewhere, depending on the direction.

Definition of MAKE DOWN dialectal intransitive verb rain, snow