Problem with conversion type of GameObject (C#)

Hello all,

I'm currently working on a RTS game and I have a problem with the implementation of a Unit Manager that is supposed to (as the name suggests) manage all units that can be selected by a player.

Now the problem I have is the following: error CS0266: Cannot implicitly convert type UnityEngine.Object' to UnitManager'. An explicit conversion exists (are you missing a cast?)

The code is as follows:

 private static UnitManager instance; 
 
 public static UnitManager GetInstance(){
    if(instance == null){
          instance = GameObject.FindObjectOfType(typeof(UnitManager));
     }
     return instance;
  }

The script is already attached to a GameObject inside the scene, I've already tried the solutions of previously answered threads on this error, I tried implementing it differently, read the manual and watched some tutorials online, but nothing seemed to work.

Any help would be greatly appreciated.

Thank you

Edit: I used the js script from the Generals thread as a reference.