Hello Juan. Yes, Microsoft does offer a free license for Windows 11 on their Azure Dev Tools for Teaching program. If you are an active student at a participating institution, you can get a Windows 11 Education product key and ISO for personal use (yes, including for virtual machines like VirtualBox) at no charge.
To get your product key and ISO:
Go to Azure Dev Tools for Teaching.
Sign in with an email issued by your school (for example, .edu domain email).
Complete the student verification process.
Go to Learning Resources > Software and search for Windows 11 Education.
Download the ISO and copy your product key.
This is a fully featured version that is great for academic testing, development, and productivity.
Best regards,