I am british citizen currently travelling in India on OCI

Can I travel from chennai(MAA) to Guangzhou(CAN) on 18th March reaching Mid day and then from CAN to Macau on 20 or 21st March first thing in the morning and back to Chennai from Macau on 23rd March .
Am I eligible for 72 hour or 144 hours visa

In order to qualify u have to start the journey either from LHR or Europe

I don't understand this

Can you please explain

Thanks