Registered and certified are different from approved, and both are claims you can ask the seller to back up.
An FDA-registered facility has told the agency it exists, which is not an approval of the product. GMP refers to manufacturing practices, and a certificate would come from an auditor. The statements on the page have not been evaluated by the FDA.
We have not verified either claim.
Ask the seller for the facility name and any GMP certificate or audit, and who issued it. A certificate with a named body and date is a good sign. Our earlier posts on FDA-registered versus approval and GMP certified cover the wording.