Activation by Email Sign-In is NOT supported on SnapGene version 8.0 or earlier.
If you have a SnapGene subscription license that requires Email Sign-In please and you wish to use on Ubuntu Linux, then ensure you have updated to SnapGene version 8.1 or later (see How do I update SnapGene?), then start SnapGene and activate by following the instructions found here Download, Install and Activate SnapGene.