What is the ethereum platform (in the context of purchasing goods on the internet)

Hey guys, total newbie (although I am technically invested in ethereum lol) and I want to buy something on the internet that requires me to pay in ethereum, more specifically, from the “ethereum platform” itself. What does this mean? I paid via ethereum from My coinbase wallet and that was not sufficient.

“Hello Sir, Ethereum is the main network for ETH and is independent of any platform. You should be able to pay from any wallet but choose the Network -> Ethereum. This means that the transaction will appear in ETH blockchain here: https://etherscan.io/address/0x466D0713Fb2aE827751402f68f81BA2F7d5Ec5F0”

These were the instructions, but I’m unclear as to how that’s not the same as me paying via ethereum on the coinbase app. Do I got to this website to make the transaction? He said I could pay from any wallet…

Anyways if anyone is willing to explain this to me like I’m 5 so I don’t lose more money, that would be greatly appreciated. Thank you in advance!