I'm being prompted to install and update for Flash, but at about 60% of the way through the install, I'm told to close Chrome, and the install won't move past that point. This is happening even if I haven't opened Chrome since turning my computer on. My default browser is Edge, and I do also use Chrome for some websites.
It's possible some other program/process is identifying itself as Chrome.
Open Task Manager > Details tab and look for chrome.exe process and terminate it.
If you're only PPAPI-based browser is Chrome (e.g. you're not using Opera, Brave, etc), there is no need to install Flash Player separately as Google embeds Flash Player in Chrome. However, they do block it by default. To enable/allow Flash in Chrome, see Use or fix Flash audio & video - Computer - Google Chrome Help
Chrome Apps like Google Hangouts keep Chrome running the background. You'll need to exit them (or kill all the Chrome tasks using Task Manager).