WhatsApp provides multiple type of access token to support their ever expanding business offering like Solution providers, Tech Partners and direct custoemrs. Initially as long as your app is in development mode, you will be able to get a temporary access token to start building your application which is valid for 24 hours only and can be used to test your application.
To get the temporary access token, you can visit your Meta Application dashboard and click on the API Setup under WhatsApp dropdown from the sidebar. You can check out the guide here in the last few steps we have already discusses the same there.
In order to get your permanent access token, you need to get your WhatsApp Business Account verified. Once your account is verified, you will be able to get the permanent access token from the same place where you got the temporary access token. You can checkout the offical WhatsApp documentation on how to get a permanent access token here