Check with your accountant. if the Accountant's Edition is used, it can open and save your file in the Premium format. Why are you more specifically trying to convert the file?

 I can't seem to get the files transferred over from the Accountant Edition into Premium how are we supposed to work together

A common misconception is that the Accountant's Edition is a "data-entry" version.  This is not true.  There are only three data-entry versions of Sage 50 Canadian Pro, Premium and Quantum.

The Accountant's Edition allows those of us who are business partners, the ability to create a new company file in any of the three data-entry versions to match what the client is using or to match what the client needs are (assuming the partner is doing the bookkeeping).

It therefore also allows us to share files with clients who may be using any one of the three versions without also installing three versions on our systems.

When sending a file to a client, many of us will create a backup.  That backup is then transferred to the client by some means, then the client should restore the file.  If you use the Restore function in Sage 50, it will also attempt to open the company file after it is recovered to the hard drive.

Assuming your accountant created your file, then if your accountant created the file in Premium and you are using Premium with the exact same release (eg. 2024.1) then it should open without any problem.

If your accountant sent you a file created as Pro, then you should be prompted to upgrade.  This should not pose a problem, just allow it to happen.  You can still share the file with your accountant as they can also open a Premium file.

If however, your accountant created the file as Quantum, then you should have received a message telling you this and that you either have to upgrade or create a new file.  But you didn't tell us this happened, so we don't know how to help you.

Bottom line is you need to discuss with the accountant whether they understood clearly that you are using Premium and what version you both have to make sure they are compatible.  Sage 50 2024.0 cannot open a 2024.1 file.  The 2024.1 version will always attempt to open and convert the 2024.0 file but not use it in it's original version.

You can tell what the *.sai file's original version is by opening Notepad, then opening the *.sai file from your hard drive.  If you tried to restore a backup *.cab file, it should have restored the file but not opened, therefore the *.sai file is still on your hard drive where you attempted to restore it.  However, I am assuming a lot of things about the process you did.