Why do I need an access key in VK for groups?

Question

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Good afternoon!
There is a group, in it received an access key. Then I make a request for publication in the group through the site on the server in this way:

https://api.vk.com/method/wall.post?owner_id=-XXXXXXX&from_group=1&message=HelloWorld&access_token=Ключ_Доступа

The result is an error:

error_code":5,"error_msg":"User authorization failed: method is unavailable with group auth.

That is, it turns out that if I want to publish in a group, I need to get my access_token? Why then do I need this access key that I get from the group?

Answer 1

The wall.post method is not available with a community token. In the https://vk.com/dev documentation , for all methods available with a community token, there is an icon next to it. If it is not there, then only with a user token.
A community token is needed, for example, for community messages.