Deneb Heatmap with Labels

I'm really struggling to get data labels to show in my deneb heatmap matrix. Very new to deneb and vega-lite so was following Daniel M-P's tutorial that he did on the Reid Havens YouTube channel. However, he didn't add the labels so I'm trying to get it to work myself, but knowing where to place the line of code is causing me problems.

Here's the code without the labels.

Any help would be much appreciated.

{
"data": {"name": "dataset"},
"resolve": {
"scale": {"color": "independent"}
},
"transform": [
{
"calculate": "datum['__selected__'] == 'off' ? 0 : datum['Transfers']",
"as": "Transfers_Selected"
}
],
"vconcat": [
{
"hconcat": [
{
"name": "Main matrix",
"mark": {
"type": "rect",
"tooltip": true
},
"encoding": {
"x": {
"field": "WeekDay",
"sort": null
},
"y": {
"field": "Hour",
"sort": null
},
"fill": {
"field": "Transfers",
"type": "quantitative",
"legend": null,
"scale": {
"range": [
"#D5E9F9",
"#FFE45E",
"#FD0E33"
]
}
},
"opacity": {
"condition": {
"test": {
"field": "__selected__",
"equal": "off"
},
"value": 0.3
},
"value": 1
}
}
},
{
"name": "Marginal bars (row)",
"width": 95,
"layer": [
{
"mark": {
"type": "bar",
"height": {"band": 0.9},
"opacity": 0.3
},
"encoding": {
"x": {
"field": "Transfers",
"aggregate": "sum"
}
}
},
{
"mark": {
"type": "text",
"color": "white",
"xOffset": 22
},
"encoding": {
"text": {
"field": "Transfers_Selected",
"type": "quantitative",
"aggregate": "sum",
"formatType": "pbiFormat",
"format": "#,0"
}
}
},
{
"mark": {
"type": "bar",
"height": {"band": 0.9},
"tooltip": true
}
}
],
"encoding": {
"y": {
"field": "Hour",
"sort": null,
"axis": null
},
"x": {
"field": "Transfers_Selected",
"type": "quantitative",
"aggregate": "sum"
},
"tooltip": [
{
"field": "Hour",
"title": "Hour of Day"
},
{
"field": "Transfers",
"aggregate": "sum"
},
{
"field": "Transfers_Selected",
"aggregate": "sum",
"title": "Transfers (Highlighted)",
"formatType": "pbiFormat",
"format": "#,0"
}
]
}
}
]
},
{
"hconcat": [
{
"name": "Marginal bars (col)",
"height": 65,
"layer": [
{
"mark": {
"type": "bar",
"width": {"band": 0.96},
"opacity": 0.3
},
"encoding": {
"y": {
"field": "Transfers",
"aggregate": "sum"
}
}
},
{
"mark": {
"type": "text",
"color": "white",
"yOffset": 14
},
"encoding": {
"text": {
"field": "Transfers_Selected",
"type": "quantitative",
"aggregate": "sum",
"formatType": "pbiFormat",
"format": "#,0"
}
}
},
{
"mark": {
"type": "bar",
"width": {"band": 0.96},
"tooltip": true
}
}
],
"encoding": {
"x": {
"field": "WeekDay",
"sort": null,
"axis": null
},
"y": {
"field": "Transfers_Selected",
"type": "quantitative",
"aggregate": "sum",
"scale": {"reverse": true}
},
"tooltip": [
{
"field": "WeekDay",
"title": "Day of Week"
},
{
"field": "Transfers",
"aggregate": "sum"
},
{
"field": "Transfers_Selected",
"aggregate": "sum",
"title": "Transfers (Highlighted)",
"formatType": "pbiFormat",
"format": "#,0"
}
]
}
}
]
}
]
}