This video will walk you through the steps to perform to open Encrypted PDFs in Adobe, using the Microsoft Information Protection add-on.
If your Office 365 organization uses Sensitivity Labels to protect PDF files, it is possible to open them using the Azure Information Protection Unified Labeling Client but this reader doesn't provide you will all the features that Adobe offers.
At the same time your external collaborators and partners, who do not have the AIP Unified Labeling Client installed, will not be able to open these protected documents.
That's why installing the MIP Add-on for Adobe is very beneficial for your organization as well as your external collaborators and partners.
Check the below video to learn how to and use install the MIP Add-on for Adobe and send it to your external collaborators and partners so so they can have the step-by-step to perform in order to open your encrypted PDFs in Adobe.