In Seurat 3, you can export the coordinates to a dataframe using Embeddings().

umapCoord <- as.data.frame(Embeddings(object = AD007[["umap"]]))

You can then add the PC columns to the meta.data as you please (cbind, sapply, paste(..,collapse=),...)

For example, if you only need to add the PCs components, without modifying them or doing other processing, you can do a simple merge

metadata_table <- AD007@meta.data
metadata_table$UMI_id <- rownames(metadata_table)
umapCoord$UMI_id <- rownames(umapCoord)
metadata_table <- merge.data.frame(metadata_table,umapCoord,by = "UMI_id")
metadata_table$UMI_id <- NULL
AD007@meta.data <- metadata_table

or if you want to be "seurat compliant"

AddMetaData(AD007, metadata=metadata_table)`

Always double check that the order of the cells between the metadata and the umap match.