The Archive is a repository of freely-downloadable games and files pertaining to interactive fiction (IF). The games and files are made available for download from the Archive and its official mirrors. You may download these games and files for your own use.
The Archive makes no blanket claim about the copyright status of individual archived files. Each file has its own license. If the file, its included license, or its description does not explicitly state that it has been released into the public domain, then the file's copyright remains with its author.
This means that the Archive or any subset of its files may not be compiled for commercial distribution without permission from each and every author whose files you would like to include. The Archive maintainers are not able to give that permission. Note that "commercial distribution" includes selling games or game compilations on online auction sites.