Recover Whatsapp data

Hello everyone,

Today my phone has been factory reset, probably because a wrong code has been entered a lot of times and therefore it was reset.

Now I would really want my Whatsapp data back, and I it should have been backed up though. I see there's 5.5Gb of backup on Google Drive, which I tried to download. Yet, it only says that existed of 150 messages, which is a tiny amount of the total amount of messages. How could I get everything back, is there a way to read / download the backup? What I should say is that I archived all the chats, to clean up my window.

Thanks in advance.