Apps manager has waiting to install just sitting not going anywhere it has downloaded and extracted
Which application are you trying to install from AAM?
Does that happen with all the applications? Try with any other application and check.
Reboot the machine and try to install.
Also, specify the operating system on which you are trying to install the same.
I tried just the photoshop first and it did what I was saying so I went on to the rest and it did the same
Europe, Middle East and Africa