something happens, otherwise, as someone warns...

Does the highlighted sentence mean "moreover, it is vital that the synthesis takes place in another way than what Giorgio Agamben has warned about"?

And why is "take" (and not "takes") used after "synthesis" in the original text?

Context:

Thus Erlebnis becomes enframed by Erfahrung, marking the synthesis of experience as ‘that which is simply lived-through and experience as something that can be accumulated, reflected upon and communicated’. It is, moreover, vital that such a synthesis take place, otherwise, as Giorgio Agamben has warned: ‘Modern man returns home at night exhausted by a hodgepodge of events – amusing or boring, strange or familiar, agreeable or atrocious – and none of them has transmuted into experience. It is precisely this impossibility of translating our everyday life into experience that makes it so unbearable, more so than ever before’