Users have been able to resolve the error 59 issue by doing the following:
https://steamcommunity.com/app/528200/discussions/0/350544272222223238/
1. Open Regedit : Run -> Regedit
2. Navigate to HKEY_LOCAL_MACHINE > SOFTWARE > Wow6432Node > Sony Creative Software > Vegas Pro - Steam Powered
3. Delete Vegs Pro - Steam Powered
4. Delete your local content
5. Re-download