To install AEM you need:
1. AEM quickstart jar file
2. license.properties file
For #1, you need to have an Adobe ID that has access to Adobe's software distribution portal: https://experience.adobe.com/#/downloads/content/software-distribution/en/aem.html
Access to the software distribution portal requires enterprise license or be Adobe's partner.
For #2 as well, you need to have an AEM license.
For both of these, you would need to reach out to your employer/client/vendor. Once you have access to the software distribution portal you can then download AEM jar file from here:
https://experience.adobe.com/#/downloads/content/software-distribution/en/aem.html?package=/content/...