Send multiple images in Postdata

Hello,

For the purpose of creating user-personalized posts, I created a form that automatically creates a draft post for a custom post type that I created.

In the Postmeta option there is unfortunately only one image field, and if I create fields for uploading files I cannot put them in Custom field. Do you have a tip so that the uploaded files automatically appear in the gallery of the automatically created Post?

Regards,

Florian