I was trying to install Amazon Games on my Lutris installation on my old laptop and ran into a curious situation. I was able to complete the installation ok as I was able to log into the Amazon Games launcher and install a game. However, I noticed that there was a command line terminal window from the installation process still running in the background even though the installation had proceeded successfully. According to this window, the installation was not complete and the only option I had was to Abort.
Things were compounded by the fact that Amazon Games was not listed in the Lutris window as being an installed application. So I had no choice but to choose to abort on the installation dialog. I chose to "keep files" and was taken back to the installation options for some reason. I tried to proceed with the installation once more and it surprisingly completed miraculously in a few seconds and allowed me to "launch" Amazon Games.
In other words, this might be a minor bug that does not detect a successful installation. However, in this case, all was not lost and all that was needed was a dummy run through the installation to completely the administrative backoffice work to get Lutris to recognize the successful install.
I hope this helps someone out there. Have a nice day :)