They issue tokens for certain actions, registration and identity verification.

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Yes, it can be a bit stressful, I had a few refusals due to the fact that could not see the boundaries of my documents, such nonsense, and there must also be an address to be confirmed. But since it was not the first time I used this company, I eventually began to trust them and therefore still found the strength to pass the identity verification.
In General, I wouldn't be writing a post about the dubious identity verification. So if you trust me you can safely upload documents. Still, this company Submission & Substance is quite well known in the crypto world and many have already used their services.
But I still hold the opinion that it is dangerous to pass the verification of your identity, so do it only on the basis of their decisions. As for me, I still don't live at my registration address, so I'm safe.