Prohibited or invalid use of HTML Tag (Critical)

Hi,

Getting following AMP error on Google webmaster, can you please cross check the same suggest.

Please find the details mentioned on the error for reference.
“Remove prohibited HTML tags, or fix attributes or values not supported by the AMP standard. AMP pages with prohibited or invalidly used HTML tags may appear in Google search results without AMP-specific display features”

Details:
The attribute ‘later"."’ may not appear in tag ‘a’.
The attribute ‘now’ may not appear in tag ‘a’.
The attribute ‘pay’ may not appear in tag ‘a’.
The attribute ‘buy’ may not appear in tag ‘a’.
AMP URL:
https://www.irctchelp.in/2017/06/buy-now-pay-later-feature-in-irctc.html/amp

Regards
Jubel Thomas

Getting following message while testing the same page.

Not a valid AMP page
Invalid AMP pages will not have AMP-specific features in Google Search results

Please help to resolve this issue
Regards,
Jubel Thomas