Question Unity editor through Reflect import BIM model，occur an error

I have Unity Reflect develop and unity pro license，unity editor through reflect importer to import BIM model，occur an error：
Exception of type 'System.Net.Http.HttpRequestException' was thrown.
UnityEditor.Reflect.ReflectEditorDownloader/<Download>d__12:MoveNext ()
Unity.EditorCoroutines.Editor.EditorCoroutine/YieldProcessor:MoveNext (System.Collections.IEnumerator) (at Library/PackageCache/com.unity.editorcoroutines@0.0.2-preview.1/Editor/EditorCoroutine.cs:79)
Unity.EditorCoroutines.Editor.EditorCoroutinerocessIEnumeratorRecursive (System.Collections.IEnumerator) (at Library/PackageCache/com.unity.editorcoroutines@0.0.2-preview.1/Editor/EditorCoroutine.cs:133)
Unity.EditorCoroutines.Editor.EditorCoroutine:MoveNext () (at Library/PackageCache/com.unity.editorcoroutines@0.0.2-preview.1/Editor/EditorCoroutine.cs:114)
UnityEditor.EditorApplication:Internal_CallUpdateFunctions ()

how to resolve this question？