Hi. Since it's a long sentence, I suggest you break it into two. Also, change provided to provides. "Camp attendees are engaged in volunteer work in local communities and at elementary schools in remote areas. This provides opportunities for them to interact closely with local residents and to achieve mutual benefits."

The tense error was caused by my negligence. Thank you very much for offering the idea of using "providing" instead.

While the sentence is a bit long, as another person already noted, it's actually correct grammatically other than the word "provided". The first part of the sentence is in present tense ("Camp attendees ARE engaged...") so "provided" needs to be "provides" to be in present tense as well. Alternatively, you could change the beginning of the sentence to "Camp attendees WERE engaged in volunteer work" and leave the word "provided" in place. However, if I were writing it, I would probably edit it to say: "Camp attendees are engaged in volunteer work in local communities and at elementary schools in remote areas, providing opportunities for them to closely interact with local residents and achieve mutual benefits." But this is just personal taste. If you correct the tense error, the rest of your sentence is fine.