Have been using this on my xiaomi sticks and boxes and has worked well.
https://play.google.com/store/apps/details?id=com.esaba.downloader
It's called Downloader by aftnews.
You can download and install/sideload any apk using this.
I found this but still no solution
Any Solutions
Factory reset will fix this problem 100%
Look up adb from your computer. Do a quick search. Its not too hard with simple commands. I use this method for all my android tv, tivo 4k and fire stick. It works great and faster once setup correctly.
you have to install an app called "downloader" from an App Store.
Since i've not used this device i do not know much about it. Can things be downloaded through a browser like a tablet, or just a download/installer app like a firestick?
If you find the "downloader" app then you can use that and perhaps check me out on YT.
Once you have the app installed the steps are the same across all device!
https://rumble.com/vmfj3j-app-store-how-to-get-apps-clickit.html?mref=2kir9&mc=2xbud
hope this helps.
You must provide the steps you follow to see if you are doing something wrong.