If you get the error in Adobe Acrobat for Windows that your "Activation Failed", please follow the steps below.
Step 1 Open Adobe Creative Cloud App
Step 2 Click on account icon which is blue circle in upper right hand corner
Step 3 Sign out of Creative Cloud
Step 4 Click continue
Step 5 Sign into creative cloud using full email address
Step 6 You may be prompted for multifactor authentication. Use Microsoft Authenticator app is you have set it up previously or use authentication phone to approve login. At this point, you may also see that Adobe Creative Cloud has updates that need to be run. If it does, run the updates listed in the app. If not, continue to next step
Step 7 Open Adobe Acrobat
Step 8 Login to Acrobat using your full email address
Step 9 Open a PDF
Step 10 If these steps do not fix your issue, please send email to email@example.com for further assistance.