Checkout link having ERR_SSL_PROTOCOL_ERROR error

Hi,
It’s an error that they independently get.
These are brandnew customers that I cannot simply ask a lot of questions because that will make them fear I’m running a scam.
I got the message by whatsapp, at least one of them claims it happened both on phone and pc.

I have invited them to the choir rehearsal that they want to subscribe to and then we will try together. We’ll see how that goes.

Rose