Here are some instructions for a number of ways to get a Leanpub book onto your device, like a phone or a tablet:
The issue might be that if you are using Chrome as your default browser, Chrome blocks files from opening automatically. First, after you click a link, it will go to Chrome and offer you an option to download the file. Then, you will see an option like "Open in..." and then you will see e.g. "Copy to Books" (for EPUB) or "Copy to Kindle" for MOBI.
Download links will open automatically if you try to open the links in the Safari internet browser.
If none of the options in the article linked to above work, you can try following these steps:
- Copy the EPUB link from the email
- Open Safari (or a browser that is not Chrome) on your phone
- Paste the EPUB link in the address bar and click "Go"
- Click on "Open in iBooks"
If you are using an Android phone, a similar process (with different apps) might work.