Hey there!
Are you attempting to install the game on an external drive? If so, the potential “disconnect” between Windows and many external drives could be the source of the issue. External drives oftentimes lack appropriate Windows-level permissions to read/write data. Please note that we do not officially support external drives due to this, and so we can only recommend installing and updating the game on an internal drive.
If you are attempting to install to an internal drive, are there any anti-virus programs installed on the machine? If so, the anti-virus/security program could mistakenly identify the Update Agent as a security threat and prevent an update or installation. More information on troubleshooting security applications here, if curious.