Macbook - Can remote into it from Windows 10 but can't control functions

I have been able to remote into my customers Macbook from my Windows 10 - He can click Allow to let me on, but then I only can see his desktop background image. I cannot open any functions on his Macbook. I can even chat with him and he can respond, but that's all. I have already had him check the Security settings on his Macbook to Alllow remote applications to control the system as he saw Teamviewer had blue checkmarks to grant remote control. I even had him turn off Firewall and I still cannot do anything except see his desktop background. What am I missing here? I have previously remoted into this same