When you apply for a loan at your home bank, you are usually required different documents such us proof of income and previous loans or mortgages. Applying for a loan online can ease the application process, since many providers have automized their processes and offer you loans without the need to upload or send additional documents.
However, this doesn't mean that you will be able to apply for a loan without any proof. Usually banks require:
a proof of stable income (which they can retrieve from the cash flows, once you have connected your bank account through your online banking)
a minimum monthly income: this varies from bank to bank but it is usually €500,-
a clean credit history
an identity card or passport