As a newcomer to SSL and Javascript, I hope you'll pardon any lack of knowledge on my part. I've been trying to research my question online, but haven't had much luck finding the answer.
Context
In simple terms, my website has a subdomain where we run a rental car booking engine within an iframe that's called from an external source using Javascript. Since transitioning to SSL, the booking engine no longer displays due to being flagged as unsecure by web browsers.
I reached out to the company managing the booking engine, and they recommended getting an SSL for the subdomain, along with purchasing a static IP on their server (I mistakenly bought a single domain instead of a wildcard one). They quoted me €130 per year for the static IP.
My limited understanding of SSL suggests to me that a static IP isn't necessary, although I could be mistaken about this.
Query
Is the static IP essential for the SSL to function properly, or will a wildcard SSL certificate solve the issue?
I recognize the need for the SSL on the subdomain; it's just the static IP requirement that I'm unsure about.
To be honest, I have some doubts about the company's intentions given past experiences of adding unnecessary charges to invoices.
Thank you in advance for your assistance.