It is unusual for the entire malicious code to be downloaded from the Play Store. It is now common practice with malware that the corresponding files are only downloaded afterwards by the carrier app in order not to be discovered.
The danger of Harly is that the Trojan subscribes to paid services. The virus can fill out corresponding forms on the subscription pages and intercept confirmation SMS.
Users should therefore be careful when downloading. A good indicator is the reviews in the Play Store. However, it should be noted that these can also be fake. The installation of security software offers additional security.