The instructions I linked to above are to install the readlang.com web-app itself to your home screen. Not to import a webpage.
If you want to run the Web Reader in Android you can install the bookmarklet. I must warn you that the process is fiddly and may not work on all websites. The instructions for this are described here: Install Readlang Web Reader on Chrome for Android.
There’s also a more lightweight bookmarklet just for importing articles to read on readlang.com. See here: Install Web Importer bookmarklet
One day I hope to offer iOS and Android apps which would make it possible to integrate with the share sheet to more seamlessly send articles to Readlang. No promises on the timeframe for this though.