If only there was a place where you can type what are you looking for and you get answers in return :) It took me 20 sec to find this so i hope it can help you

https://www.youtube.com/watch?v=c5YWFzjzVeA

If you need to pay ingots to do a plunder then you need to rank up higher in ranked battle or something like that. You need to be in top 150-200 Ranked Battle on merged server if im not wrong. And if the server is not yet merged then you need to be in top 50 in ranked battle (not sure about rules now but it should be something like that)