Vault won’t open — Keycloak “Page not found” error

Hi, I’m having trouble opening a Cryptomator vault. When I try to unlock it, Cryptomator redirects me to a Keycloak page that says “We are sorry… Page not found”, so I can’t access the vault.

In the same folder, I also have a .bkup file . Does anyone know what this backup file is, and whether it can be used to recover or open the vault?

Any help would be greatly appreciated.