CHROME
Use a computer. Chrome on Android cannot install extensions.
The Chrome Web Store link is not set yet. Follow the three pictures. The button above does not download a file. After the store listing is live, Chrome updates the extension by itself.
Click the button. Open the download. You should see a file named manifest.json. If you see a zip, double-click it once. Do not look for a second folder inside.
The same files are already unpacked in this folder list. A website cannot place a folder on your computer, so the button is that folder in one open.
Type chrome://extensions in the address bar. Turn on Developer mode.
Click Load unpacked. Select the folder that shows manifest.json. Do not select the zip. The extension is read-only. It cannot send or withdraw.