I just found a solution that I would like to provide, since it actually worked for me:
1: Head over to here and download 95 version: https://get.geo.opera.com/pub/opera/desktop/
2: Install as normal
3: Once you are signed in, you will be able to enter your passphrase
4: Profit
5: If you are on Opera GX and having this issue, you canthen Sync on Opera, then head here for and older opera gx version: https://get.geo.opera.com/pub/opera_gx/