The only (?) difference between the INT version and the US version is that the main floor is story 1 in the US and is story 0 in INT.
Either version can use metric or Imperial units - set your Working Units, Calculation Units and Dimension preferences.
I assume you have your friend's USB license key? If so, then you can download the US version (which includes the US library) from myarchicad.com by creating an account there. Rather than run the download as a 30 day free trial (or in read-only demo mode), it will simply recognize your friend's license key.
If you don't care that the main floor is story 0, then you can just keep using your friend's INT version and optionally load the US library that you download as part of the installation from myarchicad.com If you switch to Imperial Units and continue to use the INT library, you may be frustrated with the default sizes of windows/doors/frames/trim/etc as they will be converted metric units that aren't even feet/inches.
One of the forum moderators
AC 28 USA and earlier • macOS Sonoma 14.7.1, MacBook Pro M2 Max 12CPU/30GPU cores, 32GB