What To Do About An Apparently Non-Replicable Paper
I would suggest focusing far, far less on this non-peer-reviewed paper.

Publish the results you have. Use methodology that is as sound as you can achieve with the data and tools that you have. Cite previous work that agrees and disagrees with what you find. Contextualize your findings in an understanding informed by an entire body of work, not just individual papers.

The only time it makes good strategic sense to focus on replication of a particular result is if that result is influential and relied upon in practical use. A discerning reader of the literature will approach any single finding with appropriate skepticism.