Spaniard here. While I've never started a company, this resonates pretty strongly with my experience as a freelancer. In order to be an autonomous worker, you must pay 250€ a month. On top of the 21% VAT and the 16% IRPF taxes, of course, and without even having any income. According to the law, you only need to register as an autonomous worker and pay the tax if you expect to do this "regularly and as a way of living", but how this actually translates to your income was never written into law, which means you have to fight the state for it in court.

Luckily for me, I was under 30 when I did this, which means I got an 80% discount on the 250€ tax for six months. After that, the discount got reduced to 50%. Similarly, the 16% tax was on "super-reduced mode", which meant it was only a 7% tax.

Relating to the state in Spain in a non-trivial way seems to always be about navigating this ridiculous, expensive legalese maze. Don't ask me how was I supposed to fill my taxes with the autonomous community I lived on, because I still don't have a clue. Crossing my fingers and hoping they never ask for their money.