Something is not "correct" in those screenshots.
In your screen (avast main GUI -> maintenance -> registration) you need to go to the first "REGISTER NOW". Then you fill in the form. (Please do not confuse it with the last "registration form" button).
With the "REGISTER NOW" button, a form "should" open. If you see an option to upgrade to AIS, don't use it (as you want the Free edition). In such case you click ONLY on "REGISTER" (grey button) so to continue with avast Free and avoid AIS.
In the form, you need to fill in all the info, specially the name and the email info.
Then you click on "register for Free license". By this method, there is no code sent to you. It is automatically inserted. There is no file sent either.
If anything that I just described is not what you see, then please indicate EXACTLY on with step you see a difference and attach a screenshot of the exact step you see (instead of the one described here).