It likely doesn’t matter if it is for training in this case. I can’t send our codebase to a friend even if they would never look at it or use it.
The issue would be based on the terms of employment and the software license. There’s likely a provision that just says “don’t share” regardless of what the other party will use it for.
To OP’s point, if your company is paying for the sub, then sending the codebase data would be an approved use of the codebase as part of your job.