Problems with extern hdd installtion

Hello All friendly helpers

we installed windows 10 pro with DVD on a external 500gb USB 3.0 HDD target. Now I want "transfer" the windows with this external HDD to a other MAC-System with the same Paralles version.
But if I connect the HDD to the MACs I get an error and the permission for initalisation or ignoring. I click ignore and configurate an "empty" paralles maschine without a installtion. Then I want select under Hardware->Harddisk->USB external HDD. The MAC is short time busy and then he answer with an error:
(i explain in own words) Permissions missing, no read or write permissions on this drive.
I switch to ther first MAC where i installed windows and do the first paralles konfiguration and wow... i can run windows and no problems with read or write.

How is a "Portable" installation possible? We need this!

Thanks.