Domain name confusion

I know I'm going to sound like a absolute idiot but I'm struggling to understand the purpose behind a domain name and how and where to use it. I've create a domain name today on HostAfrica, but I don't understand what I should do now. I created this domain for a small business that has many random services, so there was not use in creating a website for it, I feel. So I wanted to continue making a google workspace account with the domain name. Figured out I have to pay. Tried to create a free business account on zoho mail. It send OTP codes to my email i created with the domain, but problem is, i can't manage to sign into that account to retrieve the OTP code. Point of it all is. I want to create a free business account for someone's small business using their domain name. But I don't know at the hell I'm doing or what I have to do.