The card can't do this — gambling block, no international usage, corporate card restrictions, or India's default-off rules for online/cross-border use.
Don't retry the same way. The cardholder may be able to enable the category in their banking app (common in India); otherwise, request another method.
A hard decline: the issuer's answer is final. Retrying won't change it, and it inflates your decline rate — networks watch that number.