Hello Tarzin,
Are you running under WinUAE or EUAE?
If you're running under WinUAE there is an automatic disk-swapping feature that will make installing AmosPro much easier. Be sure to have a 16 megabyte or larger hardfile prepared in advance so that it will be ready for the new files.
First, download the AmosPro 1.0 ADF disk images from the downloads directory of this website. Next, use an unzip utility to expand the archive into the directory where you want to put your ADF files. Enter the ADF disk images into the disk swapper menu from WinUAE (if available) starting with disk 1 of 6 as your boot ADF image. (In order to get the disk install to work you may have to select English as your keyboard. I found that if I entered USA as my keyboard under the emulator the text was scrambled when I typed it.) Follow the prompts for a hard drive install. (Note: you may have to use ECS emulation to get some things to work since AGA support wasn't introduced until version 1.12 .)
Once that has installed, exit the emulator and download the 1.12 upgrade disks from this website and repeat some of the procedure listed above to upgrade your hardfile to version 1.12 and then download the 2.0 update disk which includes the compiler. When you have installed 2.0 you should be in fine shape. The AMCAF extension version 1.5 is a very good one to have after you have installed the previous exercises but you may have to install AMCAF by hand rather than using its install script.
It is difficult to install under EUAE but not impossible. You have to use different keys to swap disk images and the filenames don't always correspond to the volume names of the disks. :-(
Try the above steps and post back here if you run into trouble.