Open Sims4Studio and click on, "My Projects" - select that Package File and it should open for the Texture.
If it's someone's Custom Mesh and you re-color their work - never Upload to any site, without permission.
Most people will state any allowance, on most sites - °Normally, re-colors are fine when you contact the person and give them Credit for the Mesh work.
If you are not going to upload the re-color to a site, not a big deal. I used to open files from the Sims2, to learn. I even contacted some of the hack "artisians". Some get really angry even without you uploading anything, just the fact that you even dared to look inside their file, funny stuff. It's a mixed crowd on the Ego trip.
If you are having problems seeing the CAPTCHA, please clear your browser's cache and cookies and ensure that you do not have any browser addons or extensions that interfere with the display of the CAPTCHA. Then, close the CAPTCHA window and click on the register button to open the CAPTCHA again.