The Atari port is no longer supported. It is included for those who might want to use it but it is no longer being actively maintained.
There are no substantial differences when installing gawk on various Atari models. Compiled gawk executables do not require a large amount of memory with most awk programs, and should run on all Motorola processor-based models (called further ST, even if that is not exactly right).
In order to use gawk, you need to have a shell, either text or graphics, that does not map all the characters of a command line to uppercase. Maintaining case distinction in option flags is very important (see Options). These days this is the default and it may only be a problem for some very old machines. If your system does not preserve the case of option flags, you need to upgrade your tools. Support for I/O redirection is necessary to make it easy to import awk programs from other environments. Pipes are nice to have but not vital.