The donations nominal code you refer to is for when a company make a donation rather than receive one. There is no default nominal code for donations received as it wouldn’t be applicable to most businesses. That said it’s very easy to add one to your account.
In the chart of accounts you can add a new code for donations received as follows:
Whenever you log a donation you can either post it directly from the bank by tagging as “something else not on the list” and posting to that nominal code (see a similar post I replied to yesterday).
Or you can create an invoice and log it against a line item, as follows.