You can create the ISO file yourself using AmigaForever
In the top menu go to: Tools > Build Image
Just leave the default settings
(in Content choose: Applications, Demoscene, Systems, Games)
Click the Build button
Wait for it to create the .ISO file for you.
Then when AmiKit asks for the .iso file, just find it on your harddisk and continue the installation.
OR like this:
When Amikit gives you a choice between using the ISO or the "already installed AmigaForever", just choose "already installed AmigaForever", that worked better for me