Error in FindIntegrationAnchors- Seurat package
There's a few problems with your code, first, when you do Read10X() it returns you a sparse matrix, and you need to put this into a Seurat object with meta data, before doing the integration.
So for example, i create some example data that is similar to your output from Read10X() :
library(Matrix)
epithelial = Matrix(matrix(rnbinom(100000,mu=200,size=1),ncol=50),sparse=TRUE)
rownames(epithelial) = paste0(&quot;gene&quot;,1:2000)
colnames(epithelial) = paste0(&quot;e&quot;,1:50)

habermann = epithelial + rnbinom(100000,mu=20,size=1)
colnames(habermann) = paste0(&quot;h&quot;,1:50)

Then convert to a seurat object:
data.list=c(epithelial = CreateSeuratObject(epithelial),
            habermann = CreateSeuratObject(habermann))

Then find variable features:
data.list &lt;- lapply(data.list, FUN = function(x) {
x &lt;- NormalizeData(x)
x &lt;- FindVariableFeatures(x, selection.method = &quot;vst&quot;, nfeatures = 2000)
})

Should look like this:
$epithelial
An object of class Seurat 
2000 features across 50 samples within 1 assay 
Active assay: RNA (2000 features, 2000 variable features)

$habermann
An object of class Seurat 
2000 features across 50 samples within 1 assay 
Active assay: RNA (2000 features, 2000 variable features)

Now perform integration, below I have to reduce k.filter because I have very little cells in this example. In your case, you can simply use the default settings.
features &lt;- SelectIntegrationFeatures(object.list = data.list)
anchors= FindIntegrationAnchors( data.list,max.features = 200,
k.filter=50,k.anchor = 3,verbose = TRUE)