When you created your personal Google Account, you used your organization's domain (@mycompany.com) to set up the account. Now, your organization wants to use the domain for a Google Account for the organization. In turn, you have the same address in your Google Account and your organization's new account. This creates a conflicting account.
Fix a conflicting account
The next time you sign into your personal Google Account (the original one, not the account your organization set up for you) you’ll be prompted to resolve the conflicting account. While you're resolving the conflict, your data remains safe and accessible.
Find out more about the different Types of Google Accounts.