Acast does not have a user interface from which to setup a 301 redirect. Therefore, to migrate your feed, you must email Acast at asking them to setup a 301 redirect from your Acast RSS feed to your feed.

Here is an email template that you can use:

Hi Acast Support, 

I'm moving my podcast to a new host provider and kindly request that you apply a redirect for the following show (Insert Your Acast Feed Here)

Can you please apply a 301 redirect to my new feed at (insert your RSS feed here, for example:

Please let me know if you need any more information

Thanks in advance.