Bootable USB drive for Yosemite

I'm having quite a lot of trouble creating a bootable drive for OSX Yosemite.

Every time I have tried to do create one, it fails and I am given the message

"Couldn't mount dmg /Volumes/Install OS X Yosemite/Install OS X Yosemite.app/Contents/SharedSupport/InstallESD.dmg (error code 110)Mount of outer dmg failed."

I have tried a few different things suggested in other posts on the Apple Community as well as other sites, but to no avail. I have re-downloaded the file several times through the App Store but get the same message every time. I have tried different USB sticks and a few different HDDs and SSDs. I have also tried disconnecting from the internet and manually winding the date back a few years.

If anyone has any suggestions that would be amazing, I require Yosemite as it is the last compatible and stable OS for audio software I rely heavily on.

I am currently using a Macbook Pro (late 2015) with OSX Yosemite installed, but need to get the bootable drive to return a Mac Pro (2013) to return to Yosemite from Sierra.