Zotlabs/Update
If you initially set this up more than six months ago, you might try re-entering the Friendica account password. We changed the encryption API slightly in Hubzilla4 and it may be unable to accurately determine what algorithm was being used when the password was originally stored. This has come up a couple of times when working with older stored crypto objects.
{"status":{"error":"Not Implemented","code":"501 Not Implemented","request":"api"}}
since Friendica no longer works with shared hosting accounts
What you can possibly do is select the option on the channel sources page which allows you to import these posts as yourself and drop the original author attribution. Be warned that this puts you under a great deal of risk to be sued for copyright infringement.
Then you *should* be able to repeat this with the hubzilla ActivityPub connector.
If you wish to use Friendica as the ActivityPub gateway instead, you may need to do a similar thing on that network - import the post as yourself on that system and drop the original author.