I was also having this issue, and it seems to be linked to something to do with the Microsoft .net framework, I got the .net cleanup tool (Sorry you will have to search .net cleanup tool as I don't have enough post count to post links) ran it and was then able to install the connector software using a non admin name.
This is done on the server or client? Both are newly configured from scratch a couple days ago. @redroad It seems to be caused by the registry key that enables the client to skip domain setup. Thanks for the link regarding Forefront, but I already installed it when I first configure the server.
Hello Wendy, you run the .net cleanup tool on any client that you cannot get the connector software to install on.