Your "Represent A Client" will not work to download or import information to TurboTax on behalf of someone else. TurboTax software uses NetFile which is a service for individuals filing their own tax returns. In order to use the CRA's AutoFill My Return (AFR), the individual must have their own CRA My Account set up and sign in using their own credentials.
If you are preparing returns and "E-Filing" for other individuals (clients) and charging a fee, you need to be a registered E-Filer with CRA, and use software made specifically for E-filers.
The following FAQ explains this in greater detail: Can I use NETFILE to file someone else's tax return?
And here's a link to Intuit's software for tax professionals: https://profile.intuit.ca/