I contacted support concerning this issue and they responded fairly quickly. They said to try running the launcher as administrator (among other things) and that solved the issue for me. I am now downloading the rest of the game and everything seems to be working fine. So if you have this issue of "reliable source sending corrupted data" try to run the launcher (Bethesda.net_Launcher.exe) as administrator. This file is located in the Zenimax folder of your programe files, for those who doesn't know.

Thanks to everyone trying to help out, I hope this works for everyone else!