I sent a few over to Cryptopia from MPH, no problem. [ Cryptopia Address.payment I.D. ] just in case you didn't know

What is paymentID and where can I find it?
One more question, could someone help me to setup xmr-stak? For user name I enter my MPH username but I get socket disconected error.
Go to your Cryptopia login and select Deposit then select Electroneum when asked "Please select the currency you would like to deposit to your Cryptopia account.".
You will then see a QR code and below that your ETN PaymentID and ETN Address.
To withdraw ETN from your MPH wallet to Cryptopia the address format is Address.PaymentID (note the "." is needed).
Example:
etnjzKFU6ogESSKRZZbdqraPdcKVxEC17Cm1Xvbyy76PARQMmgrgceH4krAH6xmjKwJ3HtSAKuyFm1BBWYqtchtq9tBap8Qr4M.9112dcfd10bfda2046f9eb1cd1a375e252419054959b33f44031a9431acf0af6
Can't help you with xmr-stak, I never use it.
How does one get a payment ID? Does one have to create a support ticket with the exchange to request one?