Try
1) rebooting your laptop with the USB to serial adapter still inserted see if amiga explorer can see the device COM port after the reboot.
2) selecting the usb to serial device in Windows 10's device manager and change the assigned com port from COM3 to COM1, 2, 4, or even COM5 and see if amiga explorer can now see the device's new com port.
If the above fails then the issue is probably with your version of Amiga Explorer looking for the physical COM port hardware instead of the virtual COM port created by the USB to serial interface Windows 10 driver. Try installing the latest version of Amiga Explorer.
See
http://www.amigaforever.com/ae/ to download latest Amiga Explorer; make sure that
a) you download the 32 bit or 64 bit version to match your Windows 10 32 bit or 64 bit version (see
http://www.amigaforever.com/kb/14-109 ).
b) you only install Amiga Explorer via a Windows 10 administrator account.
The license key to use for the new install is either your current key for Amiga Forever or your separate Amiga Explorer key.