How do I check email on a newly added domain?

How do I check email on a newly added domain?

Hello!
I'm confused.. So I've added a domain to zoho and created email address support@mydomain.com with a password at admin panel. Where do I login with this email and password to check the mail that goes to support@mydomain.com?

I've also created a subdomain mail.mydomain.com that points to business.zoho.com and I cannot login with support or support@mydomain.com, it only lets me login with my initial name that I've used to register at zoho.com

I feel like I'm missing something obvious :(