Can't add HDRI sky to scene in Unity 2018.4.17f1

Hi, I am making a custom map for a game, and they updated to a newer version of Unity so I had to upgrade my project. When I upgraded my project, everything went smooth, except my HDRI sky was gone. So I decided to try to add it back in the "Scene Settings" and there was no "Environment Setting".

I deleted the scene setting and tried creating a new one by right clicking in the hierarchy and selecting Rendering > Scene Settings and the tab is completely gone. I looked up the issue and all the solutions don't work. Some say go to GameObject>Rendering>Scene Settings but tha'ts not showing up, others say Edit > Rendering, but that is also not appearing. If anyone could help me with this small noob issue, you would make my day. The map was fully complete until they updated their engine causing my map to have tex ture issues.