Because of the AutoMOD configuration, files cannot be written to your site automatically. You will need to extract the file and upload the files to your server manually, using an FTP client or similar method.
As far as the MOD that you already installed, the compressed files are archived in phpBB's store directory as mod_(some 10 digit number).zip. You can download that file, extract the files, and upload them to your site to finish installation for that MOD.
A Donut's Blog
"Bach's Prelude (Cello Suite No. 1) is driving Indiana country roads in Autumn" - Ann Kish