If the official Pokemon Reloaded site will not install, work through these fixes in order. Nine times out of ten, one of the first three solves it.
Fix 1: Re-download the file
A partial download is the top cause of parse errors. Delete the file, re-download from the download page, and confirm it is the full 58.2 MB before tapping it. Compare the size in your file manager; anything smaller is incomplete.
Fix 2: Remove any old copy
"App not installed" with no other detail usually means a previous copy is already on the phone, possibly under a different signature. Uninstall every trace of the game, restart the phone, then install fresh.
Fix 3: Allow installs from your browser
Go to Settings > Apps, tap your browser, open Install unknown apps, and enable it. Without this, Android silently refuses the install. If you just installed it on another browser, remember the permission is per app.
Fix 4: Get past Play Protect
Tap More details then Install anyway on the Play Protect prompt. This warning appears for all outside-Play-Store installs. Older builds can also conflict; the old versions guide explains when a previous release is the culprit.
