Two problems after installing Opera on an old machine running Mojave

pfgpowell

pfgpowell

For several reason (repairs) I have had to go back to an old MacBook Pro running Mojave. After a clean install (to get rid of shite) I have installed Opera which is the browser I always use on the other machines. But all I get is a blank cream-coloured page.

I then went to the archive and installed a 2018 version (Mojave was introduced in Set 2018) and that installs fine etc - but it refuses to allow me to log in to synchronise my bookmarks and - crucially - my passwords.

It's driving me mad. What should I do?

PS Ironically, it this forums site accepts my log in and password!