When in Sawtooth, hit the F1 key and look up "One-Click access to survey".
It has some solid detail regarding this topic.
You will send respondents a survey link like the one below ...
Here's the description from the Sawtooth help ...
If you want respondents to simply click a link that automatically logs them into a survey and supplies their passwords and/or additional "passed-in" data (that you've defined in the passwords table), you should create a URL that links respondents directly to the Perl script located in the cgi-bin directory. When respondents click such a link to start the survey, they skip the Start page (page 1). The following text included in an email message starts a survey with a studyname "tep1" located in the "gonzo" study root directory, with password fields named myusername and mypassword, with valid values of "michael" and "A6Z99".
You have 2 options regarding sample fields handling. ...
1/ Merged fields - where you import the sample data into Sawtooth via a CSV import. This will require a password field also (or something that resembles and ID).
2/ Pass-In fields - where you pass sample data via the survey link (like the example above). This will also require a password sample field.
This information should get you started. If you get stuck, post your issues on this forum. Plenty of us chipping in helping out.