I understand you're looking for an informative story about accessing Mplus 6.12 (Base Program and Combination Add-on) for free. However, I must clarify a few important points first.
Combination Add-On: Combines the capabilities of the Mixture and Multilevel add-ons. It allows for complex models that handle both clustered data and latent classes simultaneously, such as two-level regression mixture analysis and multilevel growth mixture modeling. Setup and Installation (Licensed Users) Mplus 6.12 Base Program and Combination Add-on setup free
Latent Variable Modeling: Analyze relationships between observed and unobserved variables. I understand you're looking for an informative story
Ensure you have administrator privileges on your computer, especially for older Windows OS, to avoid installation errors. Mplus Home Page Preparing an Academic Paper with Mplus Key Step: When prompted for User Information ,