I reintalled Outlook 2016, and now I cannot preview pdf files with Acrobat Reader. Before it was ok

Enable the Acrobat PDFMaker Add-in

1. Open any Office 2016 application and click File > Options > Add-ins.
2. Select COM Add-ins next to Manage and click Go.
3. In the list of available add-ins, find the Acrobat PDFMaker COM Add-in and check if it's enabled. If it isn't, check the box to allow it.

Disable and Enable the Acrobat PDFMaker Add-in

1. Open any Office 2016 application and click File > Options > Add-ins.
2. Select COM Add-ins next to Manage and click Go.
3. In the list of available add-ins, find the Acrobat PDFMaker COM Add-in and check if it's enabled. If it is, uncheck the box to disable it.
4. Close and reopen the Office 2016 application.
5. Go back to COM Add-ins, enable the Acrobat PDFMaker add-in, then click OK.

Remove and reinstall the Acrobat PDFMaker Add-in.

1. Find an Office 2016 application icon, right-click it, and click Run as administrator.
2. Open a blank new file.
3. Click File > Options > Add-ins.
4. Select COM Add-ins next to Manage and click Go.
5. Select the Acrobat PDFMaker COM Add-in and click Remove.
6. Click Add and navigate to C:\Program Files (x86)\Adobe\Acrobat 2015\PDFMaker\Office\PDFMOfficeAddin.dll.
7. Close and restart the Office 2016 application.

Change the registry key.

1. Go to Start and search "Run." You can also press the Windows Key + R to bring up the Run window.
2. In the Run window, type "Regedit".
3. Find this registry key: HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Office\Word\Addins\PDFMaker.OfficeAddin.
4. Change the Loadbehavior key value to 3. (decimal)
5. Exit the registry key editor and restart the Office 2016 application.

You may also refer to the below link for more insights:

adobe plugin for OOOutlook

Let me know if it helps.

Thanks,

Souvik.