Firstly, you have to upload a Sales report which reflects your trading activity. Usually, it can be easily downloaded from most platforms. It should reflect:
sales amount
tax amount
countries where products were distributed
Sales report counted as 1 document. Note that you also have to upload all invoices, but they’re not counted in the quota.
Also if you receive money not directly to your bank account, but through a payment system (such as Stripe, Paypal, etc.), you have to upload a Balance statement from the system. It is also not counted in the quota. Other rules are the same as for regular accounting.