When you edit the Lead Generator, Go to Strategy, then choose the options below:

First Option 1:

Property type: Flat

Bedrooms: 4

Property Tenure: Free Hold

Option 2:

When you edit the Lead Generator, Go to Strategy Filters, then on the Advance Filters,

Choose on Property Information, scroll down then on Property Type tick Block of Flats.

Option 3:

When you edit the Lead Generator, Go to Strategy Filters, then on Advance Filters,

Choose on Keywords, scroll down then on Property Purpose, Click Include in the Block of Flats.

After that, click NEXT to Name your newly created leads generator and hit Save.