Can we use sounds from the toolbox are we allowed to use them or do we need permission?
Most likely - just be careful when using possibly copyrighted sounds or things from actual artists. Some edits won’t get you in trouble, others might, if it’s accepted by Roblox chances are they’re fine to use.
Even if they later get deleted, I’m pretty sure the uploader gets the infractions, not you. (Not certain but I think that’s how it works)
At most of the time, both infractors are punished, if your game has enough reach to cause injury to the copyright owner, use sounds of known origin, and if there is any sound that you have purchased and are copyrighted, read this.
A safe and reliable alternative is to just use sounds uploaded by Roblox - these sounds are very good and will not cause you any problems, you can get them here. I also recommend this plugin to improve your experience!
I also want to comment what @iiRealistic_Dev said.
No, the Roblox system does not always work and someone always manages to circumvent it - often the copyright redeemer is not noticed, these sounds are quickly removed from the catalog when reported.