Broken Pipe Error, installation fails

[broadbentr]

HI there, trying to install on a 2014 Mac Mini OS 11.2 booting from external SSD. I downloaded Wireless USB Big Sur Adapter-V7.pkg and expand the file. A "broken pipe error" results. I disable SIP and allow apps downloaded from "anywhere". Quit all running applications and run the installer. Installation fails. I've un-installed, re-downloaded and it still a broken pipe error and installer fails. Please any help? What am I doing wrong?

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EDIT: Thanks for your response Chris. For some reason the conversation has been locked and I cannot reply to your comment #50. As I already stated, I have disabled SIP and allowed apps downloaded from "anywhere". What am I missing?

[chris1111]

Install Fails sip is not fully disable
#50