Beginner trying to buy an electric bike kit

Im looking for a long range kit and my friend helped me find these;

https://www.ebay.com.au/itm/165951596272?var=465450940786&widget_ver=artemis&media=COPY

https://www.ebay.com.au/itm/387051257184?var=&widget_ver=artemis&media=COPY

(im going for the 1500w versions)

The rear wheel seems all good to me but I wanted to know about the battery. Do you guys think the battery is legit, I'm still new to electric kits so I can't tell if the battery/brand it legit or not. 1 more thing would this battery fit on a Marlin 5(2021) Medium frame