It can be used.
Huawei mate will not be charged with 66W, because the charger will change the power and automatically drop to the power of Huawei mate20. Huawei mate series has nine mobile phones: Huawei Mate Generation, Huawei Mate2, Huawei Mate7, Huawei Mate8, Huawei Mate9, Huawei Mate10, Huawei Mate20, Huawei Mate30, and Huawei Mate40.
Thank you for your support.
Yes, do not support fast charge will be converted to slow charge!