Sold an instagram account

HI all

I sold an instagram account a few days ago, and i did g&s of course.
Now the money is on hold for 21 days which is annoying.

I contacted the buyer saying if he could mark the item as received... he said he can't cause he does not have the OGE, so he would not take the risk. What does that mean?
I saw on multiple threads on this forum that anyone was writing something along the lines of "Account can be recovered if the seller has the email with which the account was created." and "the seller can recover the accounts since he has access to the emails.".
But how?

I mean once the email is changed and confirmed, it's that new email that counts.

Also, when i bought the account two years ago i did not even ask for OGE as i simply changed the email once i got the login credentials.

OGE means original email that the account was created with, with access to this email you can always reclaim the account so when selling Instagram accounts people want to obtain access and security of this.