business formation in Spain/business partner(s) (Madrid)

Hello,
I'm currently starting my own business here in Madrid, and the Unica Ventanilla Empresarial last week told me something that I'm questioning. They told me that in order to legally operate my business, I have to obtain an aval from a Spanish bank in the amount of 60,000 Euros. However, I'm not sure if they are correct... I'm not planning to incorporate my business (for the time being at least), but rather operate it as a sole trader (or sole proprietor).

What is your opinion? Are they correct or perhaps they misunderstood me (maybe due to my Spanish)?

If the advice provided is indeed accurate, I would be very interested in finding a business partner who would be willing to operate the business with me. We're talking about an experience-based curated/bespoke travel agency based in Madrid, but covering all of the Iberian peninsula (Spain + Portugal) and aimed at the upper-middle class/wealthy English-speaking tourists.

Thanks in advance for your assistance and any input you can provide!