Hello Sharon,

You should consult with your Colorado Extension service to check for local issues in your area, and for advi e on what trees grow best in native Colorado soils and environments.

Here in Michigan we would say that is anthracnose on maple. There is nothing at this point to do other than to keep the tree roots watered without wetting the leaves of the tree.

https://bygl.osu.edu/node/334

Also, take care to not injure roots or bark on the trunk when handling and planting. Maples have thin, easily injured bark when young. We recommend a soil test be done in the area you willplant to check soil pH, as some maples, like Acer rubrum, want acidic soil to thrive.

Next plant the tree correctly— find the root collar at the base of the trunk and plant that level with the soil, mulch without piling mulch against the trunk, and water slowly so that  water reaches 10 -14 inches down  after irrigating it.

Here is an excellent guide that shows all these points and  how to plant and care for trees

https://trees.umn.edu/sites/trees.umn.edu/files/files/tree_owners_manual_0.pdf

Maples are very hardy but do want watering during dry times in spring through fall for their first 4-5 years after transplanting.

Lastly, if you have wildlife in your area, protect the trunk for the first 4 years or so, from fall through early spring. Protective fencing and wrapping can be removed each spring and replaced each fall until bark thickens and is less susceptible to damage. Protective trunk wraps also protect thin bark from sunscald and frost cracks in winter. https://extension.umn.edu/planting-and-growing-guides/protecting-trees-and-shrubs-winter#put-up-physical-barriers-to-keep-animals-away-972411