If you used paypal check to see if you were emailed a receipt for the day it was scheduled for.
If either your paypal is linked to a card or you used a card in general, check the billing for recent payments either through the website or app for your banking and see if there was a $5.00 payment to "Minehut" (or) "Paypal*Minehut".
If there are not any payments that were made then either you didn't have enough money in your account to complete the payment, or you unsubscribed from the automatic payments to Minehut.
If there are any payments that were made and you still haven't recieved your credits, then I would make a support ticket for that a staff member can deal with the missing credits.