Can't access Zoho Invoices after receiving a request to join from Zoho invoice account owner

Can't access Zoho Invoices after receiving a request to join from Zoho invoice account owner

Dear Zoho Team, 

I have created a zoho email id. My office back-end team wants me to join the zoho invoices platform. 

These are the steps I have followed so far: 
1. Email id created and login successful. 
2. I receive a request to join Zoho Invoice. 
3. I accept the request but I receive an error that "An account already exists for this email" - Screenshot is attached below. 

Please help urgently.