software cannot find a com port

You connect a USB Flash Drive to the PC to address the issue in the screenshot

But... Your post title says "cannot find a com port" - however, your screenshot you posted is for the USB Drive preparation wizard for the OpenBuilds Interface. Not sure if you have the two products confused, but these are different from each other... One is for sending gcode data over usbserial to a Grbl controller, the other is a run of the mill USB flashdrive.

BlackBox / COM port drivers: sections 4.1 and 4.2 of the BlackBox Docs docs:blackbox:start [OpenBuilds Documentation]

Interface USB Drive prep: section 3.3 of the Interface Docs : docs:interface:start [OpenBuilds Documentation]

Make sure which product you have (BlackBox or Interface) and what you want to achieve, then follow the correct documentation pages for the relevant product

 

Then the BlackBox documentation, steps 4.1 and 4.2 applies, see above for the links.

Section 6.3 may also be helpful if the drivers are installed and you still do not see a port (typical if you caused short circuits / damage)