I don’t think you’ll need TXT records when ordering a free SSL certificate on infinityfree.Follow the guide that @KangJL tolds you.
If the system telly you that you really need TXT records,then keep in mind that all kinds of dns changes can take a few hours to take effect.
I’m aware that you are putting crypto/blockchain contents on your site which is strongly prohibited here and will lead you to suspension.Take care.
Please make sure to setup the CNAME record as advertised there. If the DNS check in the client area says ready, then do not touch the DNS records.
The error detail shown is the error message returned by the SSL provider. It can be useful for troubleshooting but it must be taken with a grain of salt because what it implies is not always what’s relevant to you.
If you request the certificate as soon as the check goes green, it’s possible that the CNAME record hasn’t been fully propagated yet.
If you try again after an hour, you may have better luck.