The easiest answer to whether you should deliver free translations when you’re just starting out: it’s up to you.
I did start out with some free work for the sake of experience and possible future collaboration, but to be fair, I could afford this from a financial perspective at the time. If you can’t, that’s a different story. I didn’t deliver these free services to companies or translation agencies, by the way, but only to ‘smaller’ clients, for lack of a better term. People, in other words, who didn’t earn much or anything at all with their texts. It gave me some experience and a bit of work afterwards, but was it worth it? Some will say it wasn’t. It did help that I could choose to translate texts I found fun and interesting.
Of course, the downside is that freelancers are more often expected to work for free or at a discount, and the more people fulfil this expectation, the more the market will start to demand this from everyone else. This is why I’ve stopped doing it myself, with a few exceptions (for example: my nephew asked me to proofread his English dissertation – he did ask how much it would be, but I decided to gift it to him instead). These exceptions are rare, however, as I now have a better idea of my worth. In addition, I get enough paid work and no longer need that experience.
Ultimately, it is up to you, but ask yourself first why you choose to work for free. Do you simply decide to do something nice for someone, or might you be a volunteer for a non-profit organisation? Or is someone taking advantage of you? Because why would your work, even as a beginner, not be worth more?