Buyer told me he has accepted my custom offer and has been charged but I do not see the order, not even pending
Since you are a new seller, I believe that a scammer, may be trying to take advantage of you. There are many of these naughty people on Fiverr that try to take advantage of newbies.
I would tell your “buyer” that you can not see an order of any kind and therefore can not start on the order, but that you will contact CS to see what is wrong. I bet when you bring up CS the “buyer” will skidadle.
As @vickiespencer has put, it could be is / is likely to be a scammer.
You seem like a sensible sort, so you won’t be starting any work for this alleged buyer until an order appears…
Remember, you’re under zero obligation to lift a finger until Fiverr (not the alleged buyer) tell you otherwise.