Please add file /etc/yum.repos.d/fedora-adalanguage.repo to your system with contents:
[fedora-adalanguage] name=Tero's Fedora RPM repository for Ada packages baseurl=http://fedora.ada-language.com/repo/$releasever/$basearch enabled=1
Note: Currently, only Fedora versions 20 (i686, x86_64) and 25 (x86_64) are supported.