I’m on 10.19.1.1166 here on a Fire Stick 4K Max (first gen) and have not had any issues with excessive crashing.
Protip: In the Downloader app’s built-in browser, add bookmarks for the Plex Android Release Thread, and the Android TV Beta Release Thread. Then, in the future, you can just jump to it and navigate to the post to get the download link without typing anything.