There is no such thing as a Bitcoin transaction URL. Bitcoin transactions are identified by a transaction-ID which looks like 31144ef6faaad902f3ec4e6f6241aa09f9ea08374abb67242039f3285414cd2e
There exist web sites run by various organisations that allow you to search for Bitcoin transaction data by transaction-ID. These websites are examples of blockchain explorers. For example you could find details of the above transaction at a number of websites including
and many others
However, any honest recipient only needs the transaction-ID, they don't need you to tell them which blockchain explorer they should be using.
Dishonest recipients will often mis-use technical terms to try and confuse you into paying them more money.