yeah from having fucked this thing up on my own, here is what i would do in order
1) create metamask account, no need to fund right away. this wallet address will be used by ZED and opensea (PM me your seed phrase, jk...)
2) create Zed account using metamask to log in (don't use email to create account)
3) link metamask to opensea.io. should just go to website and click on wallet icon and it will do it automactically.
4) in ZED, transfer ETH from any other wallet (or you can buy with CC). This will show up as ETH in ZED and metamask wallet
5) Transfer ETH to WETH with in ZED account. This will take some time and yes the fees are horrendous. It varies by time of day, so you can check around.
Now that you have WETH in ZED, this will show up as ETH (Matic) in your metamask account. This can be used to buy stuff off of opensea.io. As far as I can tell, you cannot just use regular ETH to buy ZED horses from open seas. it has to be converted.
This WETH will also fund your racing entry fees and any winnings will also be put into this account. ZED was very specific that only WETH (transferred in game) would work for buying horses. The transfer can take hours (last i did it, it only took ~20 mins) so when the drop happens, be sure to get it in early.