help please
You first have to find an appropriate broker that offers it on MetaTrader 4. Do a google search.
But please make sure you choose a reputable, licensed and regulated broker so that you don't get scammed.
And make sure to check with the regulatory services to make sure the broker's license is valid.
I opened an account on PUprime which uses the METAtrader4 and MQL5 platform but I can't find the crypto market
Did you not even research their website first to find out?
They offer CFD's of Cryptocurrencies. Open up the Symbols (Ctrl-U), navigate the symbols tree and enable the Crypto-symbols you want to trade.
If that fails, contact their support service and ask them!