Hi @anon59705555, welcome to the Community Forum!
As it stands, it is not possible to automatically add the form submitter as a collaborator of the task created from a Form. If you are the project owner and need to be a collaborator of all form submissions, you can create a rule that add you as collaborator of all tasks added to the project. I understand this won’t work if you’d like to be added as collaborator of your submissions only.
We know how much our community would like to see this feature in Forms and this is definitely something we’re keeping in mind! We have more plans coming for Forms, so stay tuned 
We have a request in our product feedback category for this feature. I’d also suggest you to upvote here: Automatically Adding Task Collaborators via Asana Forms.
Let me know if you have any follow-up questions!