In Spotler Mail+, the status Queue on a mailing means your mailing is ready to be sent and is waiting for the sending server to process it. You don't need to do anything: the mailing is sent automatically when it is its turn.
How long does a mailing stay in the queue?
How long a mailing stays in the queue depends on how busy the sending server is at that moment. Mailings from other accounts may be scheduled at the same time on the same sending server. On average, 100,000 to 500,000 emails are sent per hour. The speed of the receiving mail servers, such as Gmail or Outlook, also affects how quickly your mailing is delivered.
Read more in How quickly is my scheduled mailing sent?