>>5517266I like Zenmarket, they're usually faster than whiterabbit and tenso
https://zenmarket.jp/en/Make an account
Then when you're on the home page, click the + button next to My Account on the left, add the link to the portraits and in the description write what you want. Do this for each individual portrait you want. Know that proxies charge a small fee for each item purchased, however Zen offers the first item to a new account free.
Pic related is what I write and I've never had an issue with the 30+ portraits I've bought since 2019.