The Star Trek Adventures Quickstart Guide is a 33 page PDF (of which 12 pages are the guide itself, with the rest being non-relevant).
The Star Trek Adventures Player's Guide can be found here, but since Modiphiüs is based in the United Kingdom 🇬🇧 this link may be more useful, since FantasyWelt ships from Germany 🇩🇪.
There are two excellent wikis: