I would like to start growing an apple tree from the seed up, do I only have to worry about pollination once it has grown to a tree?
I'm not 100% sure I understand the question.
There is no need to account for pollination until the tree matures and begins to flower. For a seedling, that's probably 5-10 years. If the tree is to fruit, it will need a pollenizer (tree providing pollen) and pollinators (carriers of pollen from its source to your tree's flowers). But first the tree needs flowers.
If you are asking if there are any other things to consider in caring for a grown tree, then yes, there are other things.
Welcome to the HOS forum, LMcGarry,
Another consideration is that the apple it will produce will probably not taste like apples you've had before. It is most likely to produce small, sour, bitter apples, that may also have some sweetness. If you like those kind of apples, great. You will certainly wait a long time to find out the flavor of that apple. If you want an apple like one you've tried before, you may want to consider grafting, or purchasing a grafted apple. All of the apple trees in nurseries and all of the apples in grocery stores and farmer's markets are from grafted apple trees.