Hi we had the same issue with our GPO MSI roll out. Make sure that the share folder where the msi exists has full control permissions the the NETWORK SERVICE group and that the MSI has the same. The shared folder must not be a hidden share. It must be an AD browseable share e.g.
\\server\servershare not
\\server\servershare$ which denotes hiddenshare.
Are you doing this as a computer configuration GPO setting or User? Sometimes Apps will only install via User or Computer depending on their requirements. I guess for Adobe you are asking it to install on logon? Software products can require an answer file to take them through the installation process. This is needed for a computer deployment (e.g. auto install on startup). As a user install the user can answer the install steps so an answer file is not necessarily needed.
If user make sure that the user has the permission to install software and also FULL CONTROL permission to the c:\program files folder and probably C:\WINDOWS. Make sure you replicate the permissions through the relevant folders.
You could try to use the EVERYONE group permission, but this would open up your file security.
Also another thing to check is that your folder share e.g.
\\server\servershared is the path in GPO in the software installation setting not C:\sharedfolders\servershared as it would be if the shared folder resides on the Domain Controller.
You can map a drive as well that can work but the end machine must have the same drive letter mapped to the share path as the server.
I am sorry I have waffled on a bit. I hope this helps you
Thanks