I've fallen for that more than once when I needed cash fast, and I'm gonna be straight with you: it's a scam. No legitimate bank or platform asks you to transfer money to "verify your identity". What they do is verify data, run a check with credit bureaus, ask for documents... but never money upfront. If you already sent them the 50 euros, you're probably not getting it back. Plus, if you only saw the app on Instagram and didn't know about it before, that's a pretty big red flag right there.
What usually happens with these scams is that after you send those 50 euros they ask for another amount "to process the paperwork", then another one "for administrative fees"... and so on until you realize you're never gonna see a single euro of that 3,000. You don't even have any guarantee that these people will keep responding once they ghost you.
If you haven't made the transfer yet, don't do it. If you already did, contact your bank, tell them what happened and report it to the National Police for fraud. There are online forms for this stuff. When you look for loans in the future, stick with well-known apps or go straight to banks where you already have an account, even if they take longer to process it.