JBoss AS 7.4 binaries are not released. As for EAP 6.3.3 you have to have a subscription to access it.
For EAP versions there are only some public downloads, i.e. latest x.y.0 version.
If you need a special version or the bugfix releases like ?.?.# (where # is the bugfix release, which is only a delta and is installed on top of the x.y.0 version) you need to have a subscription. With that you can download it from the Red Hat Customer Portal.
Notice that the current available version for EAP is 6.4 and if you start with new projects I recommend to use this.
JBoss AS can be donwloaded here JBoss Application Server Downloads - JBoss Community but notice that 7.1.1 is the latest community version. There is no download for AS7.4.
The community project has been renamed to WildFly and continue with version 8.
So you need to decide based on your recommendations
EAP will be JavaEE6 compliant, longer release cycle and a longer support for productional use. Also you are able to open support tickets and access the knowledgebase.
WildFly will be JavaEE7 compliant but is supported by the community forum only and have faster release cycles without patch releases, that mean you might get new, unstable or experimental feature with the next release.