It is an interesting situation. The motherboard provides no video ports, but the website indicates that it supports APU, "by connecting external graphics card." This brief statement seems to indicate that another GPU is required, and the APU graphics will not be used.
I do not know if APU graphics can be accessed with a low-cost port converter.
The Rosewill port converter you linked above will certainly not work because it connects to PCI bus, but this motherboard has no PCI slot. Also, the Rosewill converter provides RS-232 serial ports, which are not VGA ports.
The USB to HDMI port converter linked above maybe could work. It is going to depend on the motherboard engineering. Therefore, you should ask AsRock if it is possible.