An authorization code link is a unique, personalized URL sent to you after purchasing a license for MITCALC. It is not a traditional alphanumeric code (e.g., ABCD-1234-EFGH ), but rather a clickable web address that binds your specific hardware or user account to the license.
If the online form gives you an error, the MITCalc Support Team is known for being very responsive to manual authorization requests. mitcalc authorization code link