Hello Arthur,
Yes, there should be an extra box to the right of the wrench that allows you to open the Unity project via the Wwise Launcher.
But, according to the files you sent me, you should be able to launch the Wwise project (via the Wwise Launcher) and the Unity project (from the Unity Hub) independently? Is this not enough to continue/start the certification?
If not, look in the Wwise Launcher, if you go to the Unity tab, do you see the WAG project? Do you see a version of Unity installed? If not, then you need to link the Wwise Launcher with the Unity version(s)
Hopefully this will help you
Théophile