Adjusting an angle of a collider2D to a linerenderer that is user-created

I am having issues with adjusting the angle of a collider2D to a linerenderer that created by the user. I used this solution: http://www.theappguruz.com/blog/add-collider-to-line-renderer-unity from @Swati Patel but when the collider is switched to a 2D collider, the angle is off. I tried to use a pure math way and tried to get the angle by Acos(vector2*vector2) but that didn’t work. I tried to use Vector2.Angle() but that didn’t work either. What am I doing wrong and how could I fix it? Should I use a different method to render a line? The code is a little messy due to adjusting it multiple times but the first solution is intact.

 public void addColliderToLine(GameObject startpoint, GameObject endpoint)
     {
 
         Vector2 startpos = startpoint.transform.position;
         Vector2 endpos = endpoint.transform.position;
         float lenLine = (endpos - startpos).magnitude;
 
         BoxCollider2D col = new GameObject("Collider").AddComponent<BoxCollider2D>();
         col.transform.parent = line.transform;
         col.size = new Vector3(lenLine, 0.2f);
         Vector3 midPoint = (StartPoint.transform.position + EndPoint.transform.position) / 2;
         col.transform.position = midPoint;
         Vector2 diff = endpos - startpos;
         float sign = (endpos.y < startpos.y) ? -1.0f : 1.0f;
         float angle = Vector2.Angle(Vector2.right, diff) * sign;
         //float angle = (Mathf.Abs(startpos.y - endpos.y) / Mathf.Abs(startpos.x - endpos.x));
         //if ((startpos.y < endpos.y && startpos.x > endpos.x) || (endpos.y < startpos.y && endpos.x > startpos.x))
         //{
         //    angle *= -1;
         //}
         //angle = Mathf.Rad2Deg * Mathf.Atan(angle);
         col.transform.Rotate(0, 0, angle);
         col.isTrigger = true;
 
     }