Make sure you don't have a previous version installed.
Is this on Android?
Also, are you saying that the download succeeds but the installation fails?
Hi, I was having a "The app was not installed" issue on Android 12 when using google's files app, but I could install successfully using the base file browser for my phone (samsung). I've installed loads of apks through google files so not sure why it acted up now. So for others I recommend trying another file browser if they have this issue, even if they weren't using the google files app.