How do I pair iPad mini 4 with Mac via Bluetooth when 'Mac Pro is not supported'?

You don’t pair an iPad to a pc, Mac, phone, etc.

What is it you are trying to do?

Macs and iPads don't pair with each other.

They can work together in many ways, including

• iCloud-based synchronization (Change which apps sync and store data with iCloud - Apple Support) of photos, contacts, notes, calendar entries, messages, and iCloud Drive files
• Connections to the same e-mail accounts (so you can access e-mail from either device … this can also serve to synchronize calendars associated with e-mail accounts)
• Continuity features (Continuity features and requirements for Apple devices - Apple Support)
• Shared access to Apple subscription services (such as Apple Music, Apple TV, and Apple Arcade)

Some Continuity features use Bluetooth, but not in a pairing way.