@Verytas Starting over with the source code that matches your client version (7.x) should fix the most imminent issues you have. (follow what I said before)
TrinityCore seems to be in the middle of transitioning to 8.x. Guides have not been updated yet and without external tools you cannot use 8.x client yet with TC, so I would not personally recommend trying to use the latest master branch or 8.x clients yet.