That's by design. You can't install Windows on an external disk, only on an internal one. You might need a change of plan.
... but the windows media creation tool isnt recognizing my seagate backup plus drive as a place to create the files in. My computer recognizes the drive and everything seems to be working okay, but the windows media creation tool refuses to have it as an option to throw the new windows into. Any tips to help this?

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