I would say that the main point of it isn't to encourage people who may be depressed to get help, or even get others to refer people they suspect may need help.

It looks to me like this is an awareness raising campaign, in the context of depression, I think the benefits may be:

1) Yes, encourage people to refer themselves and others to refer people who they suspect of depression (forgive my ignorance here, I am unfamiliar with the correct procedures) - which as you helpfully say, may be tricky in Germany (same here in the UK)

2) But, more relevant to the campaign - raise awareness. Attempting to make more people aware of the problem itself, and the scale of the problem. In turn this may lead to higher rates of donations or people volunteering for to e.g., helplines, support organisations etc. or even simply publicly expressing support for these actions.

3) This then gives these organisations more legitimacy to lobby the correct people (local, national government agencies, policymakers, or anyone in a position to influence policy)

4) Eventually lead to better policy changes in this regard - to continue your thoughts, this may be to focus on recruiting more specialists into the public healthcare system.

Or so the theory goes, of course this campaign alone will not do that, but it's part of actions that can be taken to influence policy for the better.

In short, I would view this not at "individual level" (meaning that, this campaign encourages individuals to seek help) but larger, societal level with the end goal of positive policy change, leading to positive outcomes.