How to get pci dss SAQ A-EP?

Question

Professional Certification

Good afternoon!
We are making a Single page product and we need to make a payment form in our own style and at the same time not have dependencies on third-party gateways.
As I understand it, we need PCI DSS certification.
Having studied level 4 and SAQ A-EP, I realized that this is what I need. We will not send data to our servers. (js->gw->callback to our servers)
What is the best way to organize certification?
If we pass the ASV scan and fill out the SAQ, what do we do with them next? Where to submit these documents to obtain a certificate?
Thanks
Raf