Upload the file in Lumin.
In Tool groups, click Security.
Click Password Protection.
Then, click Set password.
Add a password then click Apply.
NOTE: This feature is only available on the Lumin Business plan.
How do I password protect a PDF in Lumin?
Want to keep your PDF documents confidential? This easy-to-follow guide shows you how to password protect your PDFs using Lumin in just a few clicks.