The T183 Form - Information Return for Electronic Filing of an Individual's Income Tax and Benefit Return and the T1013 Form - Authorizing or Cancelling a Representative, are forms to be used by E-File providers who file tax returns for their clients. When an individual uses TurboTax, they are NetFiling their tax return to CRA, not E-Filing, so these forms do not apply to TurboTax prepared tax returns.
TurboTax is for personal not professional use and If you are filing for clients, you cannot use TurboTax. You must use one of Intuit's products for tax professionals, which will allow you to E-File multiple returns. (CRA limits NetFiled returns to 20 per computer)
Here's some more information on the the differences between E-File and NetFile: https://bit.ly/2Fh4fBO
