Use https://web.archive.org/web/20230815192027/https://baglabspublic.azureedge.net/baglabspublic/PowerBI_sample.accdb instead.
Unfortunately this has been broken for a while - as per https://video2.skills-academy.com/en-us/answers/questions/1662115/where-can-i-download-powerbi-sample-accdb
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hth
Marcin