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You don't have permission to submission the post.

Please read more WordPress Roles and Capabilities: https://wordpress.org/support/article/roles-and-capabilities/​
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So to have the right to submit articles, you need to have role permission from Contributor up.
Set role Contributor

So that all users after registering as a member can post articles, you just need to set the default role for registered members to be Contributor.
Navigate: Dashboad -> Settings -> General -> New User Default Role -> Contributor.
New User Default Role
Don't fret about it, these are great features of WordPress. Think about it, for particular users that you don't want them to submit posts anymore, then you just need to lower their role to Subscriber.
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So how can all users post after registration?