I'm confused about the title of your question which indicates that you would like to share a value accross different virtual user instances and the description of your issue where you say "the dynamic token will be valid and unique for each virtual user instance".

So do you want to share the same value accross virtual users or only extract the token from one virtual user instance and use it within that same virtual user instance on the request header?

Ok so it should easy to achieve that. You just need to use a variable extractor to extract your value and then replace your value by that variable on all your request headers.

To replace the values you can either use the search and replace on the variable extractor tab or better move your extractor as framework parameter.

I would suggest you to look at the NeoLoad documentation here

So if i understand correctly, the first user will call the API to get the token and the other virtual users should not call the API otherwise they will get a new token? Is it correct?

So do you mean that user1 should provide that token to the other virtual user instances?

In that case you can use the shared queue feature. The first user will get the token and put the value on a shared queue. Then the other user can get that value from the shared queue.

For more information, please look at the NeoLoad documentation here