Every customer should be aware of setup and select appropriate option. Just like when one may select only Raspberry Pi or bundle/kit.
There is no need to pay adapter which will
never be used!
If the usb port is not able to provide enough power for the LNB the AC adapter will be needed.
Before using AC adapter, user may try to use Y cable
User may get additional ports from mobo by bracket or front panel hub.
AC adapter comes after all above options. Of course, only highly reliable one like:
GST18
A12-P1J
Power cord provided by user anywhere in the world.