Check my last commit to see everything I changed to make this happen
Your NFT config JSON files need to look like this
{
"name": "HTML_FILE",
"symbol": "",
"animation_url": "0.html",
"properties": {
"category": "html",
"files": [
{
"uri": "0.html",
"type": "text/html"
}
],
"creators": [
{
"address": "YOUR ADDRESS",
"share": 100
}
]
}
}