In MacOS Moterey:
Had successfully downlaoded and was able to use many of the alr functions, but some (such as 'config' or 'get' displayed an error concerning a missing .toml index file. After much grinding of teeth and hand wringing I eventually discovered that I needed to activate the 'alr index --reset-community' option. Only then was I able to 'get' the 'hello' program.

OK! I solved the problem, but I would hazard a guess and say that I wouldn't be the only person new to Alire who'd experienced this issue and then spent a lot of time trying to find out what needed to be done. The number of commands + structure of Alire is significantly large, but not difficult once getting past the initial learning curve. However, there's not much clue provided on the general order of, or a broader initial set of, commands that will help reduce the relatively steep learning curve that eventuates because there are several important things to understand before one can make progress. There's an interesting diagram of the 'crates' available on the Alire site. How about something similar for the command structure of Alire showing (say) initial (getting started) paths to take in order to provide the 'big picture' and easier understanding of this significant/important facility.

Of course, it would also help if the error messages contained some clear clues on what to check out!