I asked the same question, it's linked to the email address (as a log in) you signed up with rather than a presale code. Good luck with tickets!
EDIT: looking at the last email from NCAA, it mentions a code and presale link to be sent prior to sale. Haven't received yet, hopefully any moment now with 20 min until sale time.
2nd EDIT: code is NCAAFF, link is here:
https://am.ticketmaster.com/ncaa/ism/MjRGWkZBTEw=?utm_source=sfmc&utm_medium=email&utm_campaign=MIH_20231103_Presale Starts_NCAAFF&et_rid=1858233600
See you all there!