but when I add the same LICENSE to my repo no overview is shown.
How to achieve this?
The license overview in GitHub is only displayed if GitHub can recognize your license. To recognize licenses, GitHub relies on the open source project Licensee. Common reasons for unrecognized licenses include:
The license is not in its own file. The license text needs to be, in full, in its own file, preferably
LICENSE.md. The name of the license is insufficient, as is the full content in the
You made an addendum to the license text. Licensee expects a near-perfect match to the original license text (rf. choosealicense.com). Any additional title or footnote will prevent recognition.