Now, save all the papers to your Collection by clicking "Save to Library" and selecting your collection.
From here, you can also export right out of Litmaps to a BibTeX, CSV, or RIS - so you import these papers into your reference manger (Zotero, EndNote, Mendeley etc).
ALT a litmaps page showing how to save papers and export (BibTeX, CSV, or RIS) for use with reference managers etc.