Don't bother. Please don't waste the effort. Looks like Moviestar is primarily a carrier in Spain, so I'm assuming you have the Spain version of the phone.
Looking online I see two possible phone models you could be talking about. One is the 2720a ("Fold") released in 2009. It would have support for 2G only, even if unlocked, because that phone didn't even support any 3G technologies.
If you're talking about the 2720 "Flip" released in 2019, then the European version is still 99% useless to you in the US because the phone does not support a single one of T-Mobile's 4G bands, and T-Mobile is shutting down their 3G network soon enough, meaning that you'd still be left with a phone that can only operate on 2G (which they've already slimmed down to the smallest possible sliver of spectrum anyway, texts usually work but calls are hit-and-miss).
That's beside the effort of unlocking the phone in the first place, which typically would have to be done by Moviestar officially (and there's likely to be some sort of service requirement you'd have to fulfill first), or you could take your chances with those shady third-party unlocking websites. I wouldn't recommend either option.