It appears that it isn't possible to use the HDMI and VGA port simultaneously, as apparent from one of the Question & Answer on the Amazon product page with Aukey multiport adapter.
You'll have to look for an alternative. It is advisable to go with 1st party cables and adaptors for the best results.
You can use an Apple USB-C Digital AV Multiport Adapter. It is available on Apple Retail Stores and Apple Online Store for $69.00.
Product description from the Apple Online Store web page:
The USB-C Digital AV Multiport Adapter lets you connect your USB-C or Thunderbolt 3 (USB-C) enabled Mac to an HDMI display, while also connecting a standard USB device and a USB-C charging cable.
You maywill additionally need a Belkin USB-C to VGA Adapter for connecting the VGA monitor.