You can upload multiple files under the Identity section to prove your identity and you can also upload multiple files for proof of address. When you get to the Finances section, you'll be asked to select your main income type, then you'll be able to upload as many documents as you wish to your application. If you'd like to explain your financial situation in more detail, we'd advise you to write a message in a Word document and upload it to your application.
If you've already submitted your application, you'll need to share additional documents with Let Alliance via the Residently app. Go to Support > Create new message > Referencing > Share additional documents.