I think there are two questions here. (1) Why is the buckeye tree losing its leaves so early and (2) was it planted correctly.

There are a number of possible reasons why your tree is losing its leaves in August. First, buckeye trees typically lose their leaves earlier than other trees, usually in September. Your tree is getting brown leaves very early. From your picture, it appears to be in full sun which may be a problem since buckeye trees in their native habitat are often found as understory trees getting sun only part of each day. Because we’ve had several hot, dry weeks your tree may have developed leaf scorch. Since this has happened every year and your tree seems to be otherwise healthy there doesn’t seem to be anything you absolutely need to do since it would be difficult to find a way to shade it from the hot afternoon sun. However, you could help your tree survive by watering it when we have those hot, dry weeks. Also, you could put about three inches of mulch around it to help keep the moisture in. Be sure to keep the mulch away from the trunk of the tree (See Mulching Landscape Trees (psu.edu) for a more thorough explanation about how to mulch). For more information about growing buckeye trees you might want to read Seven things to know about growing an Ohio buckeye tree (dispatch.com) and Ohio Buckeye | Ohio Department of Natural Resources (ohiodnr.gov).

As to the other question: was it planted correctly, the answer is probably. There are two theories about the best way to plant balled and burlapped trees and it seems both ways have good reasons and both work well. For a more thorough discussion about that you might want to read https://extension.illinois.edu/news-releases/tips-planting-balled-burlapped-trees-long-term-health-success.