A creative agency wants access to my Cpanel

Hey I am confused! A creative agency I hired to optimize seo for my Shopify website said they needed an admin account on my website to add meta tags and descriptions.

So I made them an admin account on my Shopify website.

But now they are saying that’s not what they need….They say they want access to my cpanel.

I am confused. I thought meta tags and descriptions and stuff like that was all added to the CMS (Shopify)

Is this a sign that I hired the wrong folks and they will be bumbling about my account settings and making a mess of things?

Thank YOu!