Try other reputable apk repos. I can recommend: apkmirror.com apkcombo.com apkpure.com apkmonk com apkfab.com More on reddit.com

Hi! Uptodown team member here. The signature doesn’t match because the file you’re analyzing isn’t the O’Reilly Media version you were looking for: it’s actually the installer for our official app. This happens because the app comes in XAPK format, which is basically a bundle containing the APK along with extra files needed for installation. Since the default Android package installer doesn’t support this format, we provide our own installer so users can easily get what they’re looking for. Once our official app is installed, a setup wizard automatically starts downloading the app you want to get. You can still download the standalone APK directly if you prefer. Just click the “All variants” button next to the download option. That way, you can verify the original file signature yourself. Everything’s explained on the download page, and we’re fully transparent about it. We never modify APK files, so the only app signed with our own signature is our official Uptodown app. We’re always trying to find a good way to offer the best possible service, though it’s true that Google and the Android ecosystem keep making things harder for alternative marketplaces. We’re open to any suggestions you might have! I hope that clears things up. If not, feel free to check out our Help Center or reach out to our support team for more information. More on reddit.com

https://www.apkmirror.com/ More on reddit.com

Uptodown employee here. All files hosted on Uptodown are scanned by +70 antiviruses through the Virustotal service. You can view the security report by tapping on the blue shield icon next to the download button. Additionally, a human team manually checks most files and removes those deemed malicious. Here's more info https://support.uptodown.com/hc/en-us/articles/360062090652 More on reddit.com