To use an exchange, you will first need to create an account. It is unlikely that you will be able to create an account for your organisation.
It is most likely that someone from you project/organisation will need to create a private account and be responsible for the transactions on your organisation behalf. Using one of the crypto exchanges available in your location, it should be possible to exchange your crypto for fiat (traditional/normal money). This may or may not be in your local currency, depending on your location.
Once converted into currency, it may then be possible to withdraw to your organisation’s bank account or debit card (sell-to-card) or your designated person may need to withdraw to their personal account and send funds as a donation with transaction statements.
Here’s are some of the more well-known exchanges (there are more and this is not financial advice). You should do your own thorough research before using any exchange.