Well this was more difficult than i thought to have an updated version installed through GPO. There are many howtos but only this worked for me. So here now the RIGHT WAY:

Download the latest enterprise version here:

https://get.adobe.com/uk/reader/enterprise/

Now save it to your local disk, open powershell and goto where the file is saved. Extract all installer files with:

PS> .\AcroRdrDC1900820071_en_US.exe -sfx_o"C:\AcroRdrDC_Deploy" -sfx_ne

Note that the filename may be different due to newer or older versions.

Great! You should now have several files, including an .MSI in the extracted folder. Now go there:

PS> cd C:\AcroRdrDC_Deploy

Now the following step is optional and only needed if you want to customize your MSI:

Download the Adobe Customiser here:

https://www.adobe.com/devnet-docs/acrobatetk/tools/Wizard/index.html

After installing the Customiser, launch it and open the C:\AcroRdrDC_Deploy\AcroRead.msi file. Do your customisations and save the transformation file next to the MSI. This will generate a .MST file.

Now you need to create an AIP folder with:

PS> msiexec.exe /a AcroRead.msi

An installer opens up. Follow the wizard and save to a folder, e.g. C:\AcroRdrDC_Deploy\AIP

Copy the .MSP update file AcroRdrDCUpdXXXXXXXXX.msp and AcroRead.mst file to C:\AcroRdrDC_Deploy\AIP

When done, go to the AIP folder and execute:

PS> msiexec.exe /a AcroReader.msi /p AcroRdrDCUpd2001320074.msp

This applies the patch. Then copy the whole AIP to a network share and go to your Group Policy Management.

To deploy the MSI now you need to add the software as ADVANCED, not ASSIGNED. Go to the Modifications tab and select the .MST file here.

Launch an gpupdate /force on your client machine and after a reboot, the latest Adobe Reader DC should be installed.