How do I deploy a Xamarin Forms iOS app to iPhone test device offsite

I have a Xamarin Forms app and I would like to distribute the iOS version to our tester, but the tester is not local, so I have no physical access to their iPhone device. I would like to do this remotely somehow.

I have searched for instructions on this, but all I find are deployments to the App Store or deployments to a physical device attached to my mac (which I have done fine). Can anyone advise the process of deploying this to our remote working tester please?

Thanks