The same thing happened to me too, it’s a problem with the new version 4.5 and its wizard that doesn’t let you skip the license, it’s mandatory.
To try to fix it, I did the following.
– Uninstall and delete the WPML 4.5.3 tables, from the WordPress panel
– Install an old version of WPML, for example v4.4.8
– Configure the installation of WPML 4.4.8, leaving the license disabled in its own wizard.
– Update WPML again to its latest version 4.5.3.