Having trouble with my client website. Using Ionos

My client has sent me his details to open up his account on Ionos as he would like me to edit his website. Now on his website when I inspect it looks like it was created by bootstrap as I can find bootstrap-light.css and bootstrap element classes like “col-md-12”. But inside his account, I can see to find access to edit his website? When I go into the web space account I can see a lot of folders such as fonts, images, videos, PHP for payment detail folders but can’t find the bootstrap folder or even the main folder for the index page? I’m struggling here to find out what this person has done. This person who created it is based overseas. does anyone know my struggles? I can’t find any way to edit the website. Is this something I might have to call the call centre?