Hello,
If you open your browser console you will have the details coming from StripeJS.
The plugin is using StripeJS from the Stripe website ; unfortunately if their library refuse to initialize due to SSL or other element, we can't log anything in the plugin since it's done from the client part.
You have to check the browser console for details.
And regarding SSL ; you can have free one thanks to "letsencrypt" :
letsencrypt.org/
Regards,
Jerome - Obsidev.com
HikaMarket & HikaSerial developer / HikaShop core dev team.
Also helping the HikaShop support team when having some time or couldn't sleep.
By the way, do not send me private message, use the "contact us" form instead.